Oldskeptic wrote:The original hunting boomerangs did not return they flew straight with skill applied. They were also more deadly or damaging than an arrow with the same accuracy. That might explain why the bow and arrow was not in use in Australia.
Still it's notable that the bow and arrow was not used anywhere on this continent with its variety of biomes. If you had a world map of land where the bow and arrow was used before western colonisation, there would be this one blank area surrounded by water and you could recognise it, Oh yes, this big inhabited area is “the continent of Australia". it’s one of the terminals of human migration:

In this Wiki pic green means early hominin occupation, yellow means Neanderthal
I know you know all this. How reasonable is your case that the boomerang would render the bow and arrow unnecessary? In open country maybe, but in forest hunting? I’m thinking that a bow can be slowly drawn or a blowpipe slowly maneuvered to aim but a boomerang needs space “to throw a cat” and is launched with a flurry, it’s a great big thing coming at the prey compared with a poisoned dart or arrow. Maybe the Australians thought the koalas were tooo cute to be hunted.
Anyway, supposing the boomerang is that superior, why wasn’t it exported through New Guinea to Eurasia? Accepting
Fenrir’s interesting evidence that Northern Australian aboriginals had contact with what is now Indonesia. It seems that technological progress hasn’t automatically travelled. Maybe it has often travelled though conquest and in some of those cases, the advanced technology enabled conquest. Thinking of the Asian riding stirrup and African iron smelting of the Bantu speaking peoples.
Some weapons seem to have been invented independently in several places, like the blowpipe but the bow and arrow maybe once only and that I still maintain that might be because it’s irreducibly complex with three components of which only the arrow might have been associated with weaponry, as a sort of spear.