” The ruling class was surely light skinned compared to the general population. That seems to be a rule in ALL societies.”
Especially in Mexico. Spaniards rule Mexico. The native population is nothing but subjects.
It is true in Senegal and the Congo also. It is true in tribes and in nations. In Central Africa if a very black man upends the ruling structure and makes himself Chief or President or whatever he then marries his children to light skinned husbands and wives. It is not a racial bias but it is a skin tone bias and it is universal. There are other implications of this trend but we don’t talk about that.