I’ve read previously where there were massive, wide-spread extinctions of megafauna shortly after humans arrived anywhere, and that widespread forest fires were the simplest way to explain which species survived and didn’t. It was speculated that the fires were the result of humans.
It’s possible.
You can do a lot when you’re at the top of the food chain.
The problem there is two fold, one the great beasties couldn’t forage in a forest and secondly the ocean and lake core samples don’t support such a massive conflagration. I support the, no single fire but mammoth meat is tasty theory. That plus there was drastically less tundra environment and more grassland (something the lake core samples and Greenland ice cores do support). Grass is hard to eat and digest.