>White has come to mean everyone of European descent
I'd be surprised if anyone in Europe even thought of themselves as 'white' until (perhaps) the post-WWII era. Wogs begin at Calais.
>Africa is also very diverse when you take into account Northern Africa.
I suppose that you could consider North Africa as a separate continent given the bordering desert. My understanding is that sub-Saharan Africa has more real-deal genetic diversity in human populations than the rest of the world put together (which makes sense given it's age).
Obviously race is a real thing. Either a giant tree of relatedness with clusters of appearance + small construction differences or simply a way to form self-interested groups (go to any prison for 10 minutes). The fascination with it as of late is unfortunate, but I'm not sure if it's a reflection of resource depletion/overpopulation, a wave of quasi-religion, or people simply forming up teams for a big fight.