Sapient paradox: Why humans got stuck in prehistory

I don't work in the field. But there is a theory unmentioned here that I'm convinced by, at least in part. Homo sapiens weren't necessarily just smarter than neanderthals and other proto-humans. There is a lot of evidence, much of it recent, that neanderthals were very intelligent indeed.

But Homo sapiens worked together. They were smarter in a more communal way. This can go a long way towards accounting for both their dominance of other archaic humans and the delay between their emergence on the world stage and the development of civilization.

The sapient paradox seems to me to make two assumptions. Intelligence is sufficient for civilization, and Homo sapiens were exactly the same species 60,000 years ago as 20,000.