Me too, but blacks do make sense in Greyhawk. The continent of Hepmonaland (just south of the Scarlet Brotherhood and northern tip visible on the main Greyhawk maps) is basically sub-Saharan African. The Touv race of humans from this continent are rare in my campaign, but in my campaign certainly not absent from the major maritime cities around the Azure Sea and the southern Solnor Ocean.I have kept some people that are black in Pazio adventures as being black despite it not really making sense in my renaissance version of Greyhawk.
Most notably, that includes Sasserine and Cauldron (the setting of 2 of Paizo's 3 Greyhawk Adventure Paths), and in my mind the Wild Coast (including Greyhawk City), the Hold of Sea Princes, Rel Astra, and Gradsul in Keoland.
The Greyhawk "Africa" source book is "The Scarlet Brotherhood", from the post-1998 TSR revival of Greyhawk, so likely published ~1999. Hope that helps.