When the first British settlers arrived, they came with their own ideas about what land ownership was. In their eyes, the land was "Terra Nullius" and there was no visible sign of it belonging to anyone as there were no permanent dwellings and no existing laws and customs that they could see.

You answer is not relevant to this debate. This debate is specifically about the Mabo Decision in AUSTRALIA which was a battle between Indigenous AUSTRALIANS and the Australian Government.