Since the quote in question is from 18th century anti-slavery activist Thomas Clarkson’s famous essay, “An Essay on the Slavery and Commerce of the Human Species, Particularly the African Translated from a Latin Dissertation, Which Was Honoured with the First Prize in the University of Cambridge, for the Year 1785, with Additions”, I doubt whether he was reporting on an actual, observed phenomenon. Much more likely that he was “reporting” a completely manufactured factoid in order to further his anti-slavery agenda: “Africans are born white, so they’re really just like us…”
This can also be said of Caucasian babies. Caucasian children can have much lighter hair as toddlers than they do as older children; they start out blonde and are frankly brown-haired by age 7 or 8.
And of course there’s the proverbial fairness of “skin like a baby’s”, as in, “He dropped trou, and his buttocks were like a baby’s”. IOW, very pale.
I have. My Walgreens store is in the “disadvantaged” section of town, and I’ve seen newborns of every shade of black, the same way I’ve seen their parents in every shade of black.