Egypt has been settled by people of different ethnicities for thousands of years. Levantine people, black Africans from Sudan and Somalia, Greeks and Romans, Berber people from North Africa, in addition to the "native" population which, based on ancient Egyptian art, looked very similar in skin tone to modern Egyptians. Basically, ancient Egyptians were not a single race, just like how, say, Russians, are not a race.

There were certainly black Egyptians from early on in their literate history, but they were never the majority.

Just look at Egyptian tomb paintings. People are portrayed as having brown or reddish-brown skin (with women generally being paler due to the ideal of women performing indoor work). Why would they portray this in art if people in real life were black? That makes no sense.

Never trust fringe crazies like Williams. There is generally a reason why no one agrees with them.