Only part I can refute is point 1:

There's substantial evidence for cultural dissemination across Eurasia, largely by Europeans. In particular there's every reason to believe China left the neolithic because Europeans traded bronze with them and eventually they gained hold of the technology.

However this isn't an excuse: Africans also were connected to global trade networks, in particular Punt (modern Ethiopia) and later the various west african kingdoms which is how they got their hands on rice.