- Among those who believe in intellectual differences among human groups, very few believe Europeans are the most intelligent group. The prevailing opinion you would find is that both Ashkenazi Jews and East Asians (your second example) are more intelligent on average.
- Northwest Europeans encountered intense selection over a Millennia starting around 300AD through a couple of mechanisms: The Church banning cousin marriage, and Biparte Manorialism. This resulted in the destruction of kinship networks, established the nuclear family, and selected for the high-trust peoples that enabled a kind of society you can still only find among those peoples.