Honestly? As far as animals go, North America's definitely the more dangerous in aggregate than Australia. Australia has a few really dangerous snakes and bugs, and then the emu...
North America has... let's see... Moose, bison, wolves, brown bears, meaner whiter brown bears, five of the top ten deadliest spiders (two of which are shared by Eurasia, two others in South America, two others in Africa, and Australia gets one)...
Australia has... Emus, which mostly leave humans alone, one of the deadliest spiders, and a handful of deadly marine life. Oh, right, and some toxic birds. But it's your fault for eating them.
South America- some bugs, a dangerous cat, some dangerous snakes, some crocodilians, and some really dangerous amphibians.
But, if you want the deadliest animals on Earth... you either want Africa or India.
Africa is mainly the disease-carrying bugs, but also the megafauna- you'd think it'd be lions or crocodiles, but no, they mostly leave us alone. Hippos, on the other hand... no chill. They are anti-chill. They're like honey badgers, if honey badgers were the size of a small car. Oh, right, and two of the top ten deadliest spiders.
India's claim to fame includes "the most effective human predator that we haven't driven extinct" (re: tigers), "the snake responsible for half of all fatal snake bites on Earth", "Both of those aforementioned Eurasian deadliest spiders", and "all the same deadly marine life as Australia". Also the occasional bison or buffalo attack.
But, yeah... overall, North America beats Australia. South America probably about ties North America. Africa outclasses all of us, and then India... How do humans even survive in India? Let alone so many.