First. We do come from Africa much less a black origin.
The bible says babel is where men separated to fill the earth.
The black colour and other black attributes is a extreme reaction of the human body to a hostile envirorment. Likewise white is a extreme reaction.
The colours in between are more close to the original.
I suspect skin in the beginning was more adaptable but after all the adapting it shuts down doing any more.
The whitw skin and hair is for one purpose. To allow the benifits of sunlight to be absorbed by the body. The cloudier . over the year, it is the whiter you are. Along with this is also that women are faired because they historically would of covered more of thier body for decency and perhaps more sheltered.
The people in the more cloudy area, very north Europe, had such a cloudy issue that thier bodies reduced almost all pigmentation to red spots and hair. Red headed men, despite being related to the hairist men in the world, shave very little and likewise redheaded women have the lowest hair count of europeon women who have the most hair of any women.
I believe also blue eyes are the result of pimentation issues.
White skin was a extreme reaction to problems met by the first settlers. Finns are white and yet a very asian people (by language) I believe.
The asian skin doesn't need protection from the sun but also didn't have lack of sun issues. Thier hair betrays this
The Asian head is made to deal with a strong dangerous wind. So the eyes, upper cheeks, and uncurling hair are all to withstand the forces of wind.
They were not in a wet world so little hair is needed and pigmentation loss was not needed. They bummped into the ice age about 1800 B.C and so God provided thier bodies with an ability to adapt quickly. Not by natural selection.