Short answers, pulled from the story.
The Australian continent sits in the middle of a tectonic plate, making it unique among all landmasses on Earth. It is the lowest, flattest, and oldest landmass on Earth due to its stable geological history with no active volcanism today.
Archaeological evidence shows Indigenous Australians arrived at least 50,000 years ago after migrating from Africa to Asia around 70,000 years ago. More recent research suggests possible arrival dates as early as 65,000 years ago.
Dutch navigator Willem Janszoon made the first documented European sight and landing on the continent in Cape York Peninsula in 1606. Dutch explorer Abel Janszoon Tasman circumnavigated parts of the coast and discovered Van Diemen's Land now Tasmania, New Zealand in 1642, and Fiji islands.
The Commonwealth of Australia came into being when Federal Constitution was proclaimed by Governor-General Lord Hopetoun on the 1st of January 1901. Charles III serves as King of Australia with his role represented by the Governor-General at federal level and Governors at state level who act on advice of government ministers.
Some 83% of mammals inhabiting the continent are endemic to Australia because Marsupials and monotremes out-competed placental mammals only within Australia-New Guinea coming to dominate there. New Guinea contains 284 mammal species including three orders of marsupials plus rodents and bats where about 195 of these mammal species representing 69% are endemic.