The increase in intelligence over the past 10k years (shown in Europeans) explains a lot.
Why was cultural change so slow in the deep past? Why was invention so rare? Because people weren’t smart enough yet.
I’ve seen anthropology professors claim that all homo sapiens populations, even hundreds of thousands of years ago, just had to have the same capabilities as high-performing groups today. Not the case.
Similar changes probably happened in at least one other population ( East Asians) but not to the same extent, or at all, in others.
Which is why populations differ significantly in IQ today. Even populations that had common ancestry ~50,000 years ago, like Finns and Australian Aborigines.