You’ve got to understand that when the Brits showed up, the aborigines were still in the stoneage. The Maoris even thought they were weak people. 

If anyone else had colonised this country there would be no aborigines today. They wiped out the Tasmanian mob and could easily have done the rest but that wasn’t their way.

And colonisation was inevitable - such a huge landmass was never going to just be left alone in that era.