Are you aware of the Australian indigeneous ethnic group called the Torres Strait Islanders? They are considered ethnically distinct from Aboriginal peoples in the rest of Australia. There are about 100,000 of them. They reside on the islands between the north tip of Australia and the south coast of Papua New Guinea. Thus, I would qualify your post by saying: The vast majority of Australians have little contact with PNG, but the Torres Strait Islanders have had contact with PNG peoples for thousands of years.

You can learn more about them here: https://en.wikipedia.org/wiki/Torres_Strait_Islanders