Shayne Williams' mother Iris never read a history book. Yet she always knew about the 50 or more fishing spears and the shield that Captain Cook's men stole from her Aboriginal clan at Kurnell in Sydney during that first fateful encounter over eight days in April, 1770. Other locals say "ole Jimmy Cook stole our fish" as if they were chatting about today's catch.

"When we were growing up, mum would say, 'Those fellas took our spears from over there'," says Williams, a 55-year-old Gweagal elder, standing on a ridge where the artefacts were stolen from his people's huts.

It is an often-told story in the family's oral history, so much so that Williams tried to bring the spears back to Australia – if only for a visit. In 2002, he discovered they were in the United Kingdom, but red tape and an outcry about the need to return them permanently to Australia defeated him.

His mother died in 2011. But this month, two of only four surviving spears will finally return to Australia for the first time in 245 years.

Along with 150 other objects from the British Museum, the spears will go on show at the Encounters exhibition at the National Museum of Australia. Together they represent the oldest artefacts collected from Aboriginal and Torres Strait Islander people. The exhibition also includes more than 138 contemporary Indigenous objects, mostly from the Australian museum's collection. Some are new, adding a contemporary chapter to the stories told in the British Museum's collection. They include a funky pink Harbour Bridge covered in local shells by an elderly Indigenous artist Esme Timbery, contemporary videos and two new spears made at Kurnell by Williams' nephew Rod Mason.

The two men were emotional when they saw the photos of the lost spears during consultations that the NMA started more than three years ago with 27 Aboriginal communities to uncover the stories and history.

The spears taken by Cook were nearly identical to the ones the Williams' family and their clan made on fishing holidays. The old ones used sinews from a wallaby's tail to tie the prongs together, while Williams remembers using bits of old prams from the tip to bind them. "It feels like we are carrying on a tradition," he says.

Plundered, looted and seized

Like the Kurnell spears, many of the show's objects were taken from their original owners. Others were the spoils of battle. They were plundered, looted and seized as the local people's rights were violated and ignored.

A rainforest shield, a woven basket and a wooden club from Queensland, for instance, were taken during repeated and violent land grabs in Rockingham Bay by Scottish-born sugar farmer John Ewen Davidson. On June 24, 1866, Davidson wrote in his diary of a confrontation in which some Indigenous people were wounded and one killed. "There was plenty of blood on one or two shields," he wrote.

A few were given in love and friendship, including taap​ knives probably given to West Australian settler Alexander Collie by his Aboriginal guide Mokare. The two men asked to be buried together.

The NMA's director Mathew Trinca says Encounters is the museum's most important project yet; an opportunity for Australians to develop a more "nuanced understanding of Aboriginal and Torres Strait islander history, and their extraordinary longevity in this land".

Every object tells a story about an early encounter, he says. Most were marked by the same misapprehensions and misunderstandings that marked Cook's first days at Kurnell.

It has taken eight years to make the exhibition a reality. It began when NMA senior curator Ian Coates visited the British Museum in London in 2007 as part of a curatorial exchange program. Once there, he realised the vastness of the institution's Indigenous collection and the importance of the histories behind the objects.

The show is bound to be controversial; it will likely trigger demonstrations and certainly ignite debate over whether the artefacts should return permanently to Australia – something that divides the Indigenous population as well as outsiders.

The museum's response? Modern Australia can handle it.

"We don't need to be fearful of discussion and debate," says Trinca.

Kurnell and the first encounter 

The spot at Kurnell where the English first landed is marked by a simple plaque. It notes that Cook's young relative Isaac Smith was the first Englishman to walk on Australian land. Not far away, another memorial marks the place where the first white man – a Scot called Forby Sutherland – died a few days into Cook's first visit.

"You don't see any monuments to us," says Williams with a chuckle. His people have been living and dying here, without markers or plaques, for 60,000 years or so.

Overhead, planes take off from the Kingsford Smith runways, their unnaturally straight lines contrasting with the natural curves of the beaches and headlands. Within the bay that yawns from the headlands, people fish against the industrial backdrop of the nearby Caltex refinery.

In 1909, a booklet on immigration and tourism declared: "What Plymouth Rock is to America, so should this memorable spot on the south shore of Botany Bay be to Australians. Not since Columbus had such a discovery been made. Birthplace though it is of the great nation Australia is destined to be, it is comparatively little known, and certainly little reverenced."

Even today, few people seem aware that this was the birthplace of modern Australia – and the myth of terra nullius​.

It is here that relations between black and white Australians got off to a "bad start", says Peter Yu, the chairman of the NMA's Indigenous Advisory Committee.

Instead of negotiation, it was authority at the end of a musket, he says. King George III's instructions to take possession of the Great Southern Lands with the "consent of the natives" were ignored.

For days before the Endeavour arrived, Aboriginal tribes lit smoke signals, warning each other that something was coming north around the eastern seaboard towards Kurnell.

When the Endeavour landed, the locals yelled, "go away!" or "warra warra in the language", says Williams.

Two Aboriginal men approached the Endeavour as the white men landed. They were defending their country from invaders.

Cook thought they were welcoming the newcomers. "I thought that they beckon'd to us to come ashore; but in this we were mistaken,"  he wrote in his journal at the time.

Cook brought a Tahitian native with him, believing he could translate the local language into English. "That in itself is instructive," says Yu. Cook had assumed all Indigenous languages were similar.

Williams, drawing on Gweagal oral history, says the first encounter took place on "a nice sunny day", but one full of fear and confusion. "For Aboriginal people, these strangers came into the bay, and we couldn't make out who they were. They were dressed differently and we weren't sure if they were ghosts. We weren't sure if the Endeavour itself was a floating island. We suspected it was. And we saw sailors go up and down the masts and we thought they were possums.

When the two local warriors approached, a musket was fired, wounding an Aboriginal man who then grabbed the shield that is included in the collection. The botanist Joseph Banks reported the incident in his journal: "Defensive weapons we saw only in Sting-Rays [Botany] bay and there only a single instance – a man who attempted to oppose our Landing came down to the Beach with a shield of an oblong shape about three feet long and one 1/4 broad made of the bark of a tree; this he left behind when he ran away and we found upon taking it up that it plainly had been pierced through with a single pointed lance near the centre."

Within a year, the spears had been given to Trinity College in Britain. Soon after, the shield was given to the British Museum by either Cook or Banks. Over the years, the Aboriginal Indigenous collection in the British Museum grew to contain another 6000 Aboriginal and Torres Strait Islander artefacts – rarely seen – from similar encounters across Australia. 

Australia's Elgin Marbles?

Now it is time to bring these objects home for good, says Gary Murray, the spokesman for the Yung Balug clan, of the Dja Dja Wurrung first nation, based in Boort, Victoria.

If an Australian had nicked the British Crown Jewels, and put them on display in the National Museum in Canberra, the Brits would be knocking down the doors, he says.

Yet the British have kept his people's most precious and rarest artefacts; the only surviving examples in the world of Victorian etched barks (which will be included in the exhibition in Canberra) taken by the settler and early photographer John Hunter Kerr prior to 1854. The barks were smoked and blackened over an open fire, then etched to tell a story. Each one was valued at more than $2.5 million by the British Museum.

"White man has stolen our land, our languages and de-culturalised, dispossessed and dispersed us ... and taken our cultural materials and put them in the place of the people who essentially robbed us, the king and queen of England," says Murray.

"They have stolen evidence for international court cases that define our sovereignty and rights. One bark actually shows our people with spears, and it shows two troopers with muskets.

"These barks are evidence that our people fought for their country, same as the Brits fought for their country in World War I and II."

By the time Kerr settled in Boort, north-west of Bendigo, most of the clan had been decimated and dispersed, their lands appropriated by settlers according to a report by Elizabeth Willis, an emeritus curator with the Museum of Victoria and a senior fellow with the State Library of Victoria. Kerr's photos documented the end of an Aboriginal race that he believed was doomed from colonisation.

Murray estimates there are only a thousand Yung Balug people left today, including his five-year-old grandson, Wilun, who is very likely the thousandth generation.

The barks have only been exhibited a few times, and the last time was controversial.

In 2003, Murray and Gary Foley, the Victorian scholar, author and activist, hatched a plan to seize the barks when they were loaned by the British Museum to the Melbourne Museum to mark the Australian institution's 150th birthday.

The pair convinced a court to use a little-known provision of the National Aboriginal Cultural Heritage Act to secure the artefacts. Faced with pressure from the British and legal action from Melbourne Museum, the clan lost the case, but they found a friend in the Greek community, which is lobbying for the return of its Elgin Marbles.

"Our view has never changed. We want them home. That's what the dialogue should be heading for," says Murray. "We are sick of Encounters, discussion and dialogues, emails and the rest. We want a decision and date on when they will be returned for good."

One of Australia's most respected Indigenous leaders, June Oscar from Fitzroy Crossing, left a British audience in tears when she spoke at the opening of a display of many of the items at the British Museum in London earlier this year.

"White men took these from our land and brought it to a foreign place," she said, speaking in English and Banuba, the language of her people. "These materials have names in our language. The trees, stones, grasses still grow and still stand on our lands. These materials sit in a bigger story. They sit at the centre of that story forever. We will never forget this story."

Each object dug up from the depths of British and Australian museum collections, she said, conjured a range of emotions: "joy and wonderment at our remarkable living cultural heritage, and pain, outrage and resentment emanating from the colonial wars, never fully acknowledged by the Australian state. Wars that saw countless violent deaths, causing profound cultural and societal loss and intergenerational grief".

Oscar, who has been part of the NMA's consultations, knew these emotions first-hand. Yet she concluded by saying the objects they should travel the world to educate people before returning to her people for good.

To Williams in Kurnell, "it is a miracle the spears still exist today". Whether they were stolen or collected or whatever, his people now have the chance to see them again. Without museum preservation, the organic materials would have been unlikely to survive.

"They represent what happened at the time of the landing and they are tangible proof that this country wasn't terra nullius," says Williams.

"There was a whole philosophy behind the spears. I hope people will realise that there was an entirely different culture here in 1770 and it was a sophisticated culture, with a very profound way of living in harmony with the environment. Everything for us, everything, has a spirit, even innate objects like stones and mountains."

"Our histories might not have been a good one, but they were a shared history just the same. We have a shared history, a shared present," he says. "And we have a shared future."

Encounters is at the National Museum of Australia, Canberra, from November 27 until March 28, 2016.