"Appears to have stayed put" is very interesting. For as long as I remember, the theory was Aboriginal settlement was in waves over a long period of time, from different regions depending on what routes were available at the time (land bridges etc.). Waves of settlement pushed existing populations further south, with the oldest group down in Tasmania (well documented as wiped out by Europeans). Now I'm reading "a single, rapid migration along the east and west coasts", and extrapolating from that the significant racial diversity would be divergence over the last 50,000 years.

(https://www.nature.com/articles/nature21416 linked from the article)

(A tenancy to stay put might also help explain the amazing density of languages)