Justyn Knight isn't a marathoner, but his prowess in distance running shows that it's entirely possible for distance GOATs of West African heritage to emerge. (Knight is Barbadian on his father's side, and Jamaican on his mother's side.)
Just based off of looks, I would guess Knight is about 30-40 percent European(average black person in America is about 20-25 percent European). Me personally, based off of all the American half white/half black 800m runners(like half of the top 25 American 800m times come from African Americans who also have a good percentage of European genetics), I believe this group (about half European and half west African. Not politically correct to say, but this hybridization I believe can create the best distance runners as far as genetics are concerned.) are one of the most untouched groups with the most potential/talent. We need to do more to get this population into distance running.