Yeah, it really is fascinating. Sorry, my previous comment didn't talk much about the Cushites. We have a large Kenyan Somali population - close to a million - and an even larger diaspora from Somalia with residency or refugee status, because of the civil war in their country. The Somali myth of origin, if I remember my high school history, goes something like this. A Yemeni man marries the daughter of a man - ethnicity not specified - called Darrod. Assuming Darrod was black in the typical sense, this story might point to a "biracial" origin of the Somali. The Ethiopians on the other hand, have a story about a creator making humans out of clay. Those who stayed too long in the kiln became black and were placed south, those who didn't stay in long enough became white and were placed to the north and the Ethiopians who stayed in for just the right amount of time were placed somewhere in the middle. I read it when I was a kid, so I don't quite remember if it placed any distinctions between the Tigre and Amhara, the most dominant tribes in Ethiopia. I assume it's the same for the Erritreans, as they were essentially a single nation at some point.

Cushites - are "Black" in a political sense, maybe less so in a cultural sense as I've been made to understand that Ethiopians generally don't see themselves as lowercase "b" black.

About the gradient thing, black people have a huge spectrum of different skin colors, even within the same family. My Mum for instance, is light skinned. My sister and I are quite dark. The funny thing is we started out really light skinned as children, perhaps till we each turned three. I've heard some kids start out blonde and end up with dark hair? I find it all quite interesting.