I'm pretty skeptical that cultural change was meaningfully slower (except as limited by effective population sizes). Cultural change for early humans is nearly invisible in the material record. Imagine that all archaeologists of the far future find nothing from the current era except iphones without working storage. Do they indicate a unified global culture without cultural change outside WWDC?
Obviously not, even though there are aspects of a shared global culture indicated by their global distribution. Material culture is related to culture, but it's an imperfect and imprecise record. The same issue occurs with correlating culture with genetics or language.
Sure, but this is true of neanderthals as well. So we can't say we are especially creative or dynamic in our culture. We can say that our material culture, that small fragment of it that was preserved, was static.
That was the point: I also wouldn't say that about neanderthals.
The evidence on the ground is of course, limited. But it's a fairly common view among anthropologists/archaeologists that our perspective on ancient societies is immensely limited by the material record, hence the generally positive reception to Dawn of Everything despite its sketchy details and interpretations.