It is handy to have a word that describe a person’s cultural heritage as that contributes so much to who they are. ‘Black’ is useful in so far as it refers to some social aspects of families with African roots, however distant, but ‘African’ is so much better and as a reference to culture it could theoretically also apply to people of any colour, even white, who came from that culture. Likewise growing up as a person of colour can be a very different experience ( due to the way people react to you) to growing up ‘white’ , (this applies to anyone growing up in a minority setting and in some ways this argument is similar to that in the thread on calling youself a woman).
Just as a matter of interest, until recently, African albino babies were often killed or shunned ( as were twins).
Americans still refer to a tarmac surface as blacktop. Don’t you just love them for calling a spade a spade?
I passed a black sheep amongst a flock of white ones, yesterday - should I call it a sheep of colour?
Scientifically, white light contains the wavelengths of all colours and black light contains none, so who is a person of colour?