They had a tiny sliver of Africa, the very northern part, where the people live in mountains and are pale skinned and look like other Mediterraneans. Sub Saharan Africa is where you find the black people, not above the Sahara. Sure there were some black people that made it up there but it is no way the norm. US has far more diversity, there are people from all over the world in the US. Rome had mostly europeans with some north africa and arabia.

Egyptian royalty were Mediterranean looking like the Romans. A lot of them came from places like Greece and Cyprus to rule over Egypt, they were the upper classes, ruling over darker-coloured lower classes. So your point doesn't make sense. Just cos Netflix casts Cleopatra as a black woman doesn't mean it's true. It's not.