There's a lot of divided opinion there in the informed community, not many think that humans soley wiped out the megafauna, a good number question whether they played a significant decisive role in their demise, most think humans killed and ate a few.

What is certain is the same change in global conditions that allowed humans to walk to Australia and later filled the moat coincided with the fall off in megafauna. There's correlation, but causation??

The divided opinions:

Climate change not to blame for late Quaternary megafauna extinctions in Australia (2016) https://www.nature.com/articles/ncomms10511

Humans killed most of Australia’s megafauna: study (2017) https://www.australiangeographic.com.au/news/2017/01/humans-...

Did people or climate kill off the megafauna? Actually, it was both (2019) https://theconversation.com/did-people-or-climate-kill-off-t...

Humans coexisted with three-tonne marsupials and lizards as long as cars (2020) https://theconversation.com/humans-coexisted-with-three-tonn...

    It turns out humans coexisted with the megafauna over about 80% of south-eastern Sahul for up to 15,000 years, depending on the region in question.

    In other regions such as Tasmania, there was no such coexistence. This rules out humans as a likely driver of megafauna extinction in those areas.