I think your last statement about the "true Negro" type is very correct. That term has come up on quite a few occasions, especially in the European Anthropological cirles of the past two centuries. I agree that there have always been regional variations between Black people, just as between White and other groups. Most of the ideas on the existence of the so-called "classical Negro" came from observing people of tropical west Africa. I have always noted the difference between most Sudanese and Bantu speaking Blacks for instance.