Title pretty much says it already.

If the majority of players playing D&D are white and male
If over 90% of the human NPCs in the Forgotten Reals franchise* are white
If, according to Larian itself**, the average character made is white and male

Then why is the default human character a stereotypical black woman?

This is even more weird since the developers do track the character designs and know exactly that the players create white male characters mostly. If they would just simply sort the faces, colors and other options by popularity, they would also increase the usability of the creator by magnitutes.

I can't find any good reason for this design decision apart from a political agenda being pushed into a game.

* Baldurs Gate 1 and 2, Icewind Dale 1 and 2 together have less than a dozen black human NPCs among several hundreds - the only one I can actually recall is Dynaheir
** Hotfix #4 News