Were they really all Black?

I have a friend, a white woman, who is currently deeply in love with a Black man who has gotten her interested in ancient Egyptian culture. She posts about her study of hieroglyphic writing (I've forgotten which style), which I envy her for, and sometimes raves about the "whitewashing of Egyptian culture". According to her and her beloved, all of ancient Egypt was populated by African Black peoples (I can't think of a better way to word that and I apologize) and none of the ancient population was Arabic or southern Mediterranean in physical type. I don't reply to her posts, for the most part, because I'd rather not get into an argument that is so heavily based in emotion about reclaiming Black pride of heritage, but I don't agree with her either. Certainly some of the population was Black, and some of the Royal families were. We have written records of that, especially of the saving of the culture by the Nubian Kings during the time of political instability preceding the twenty-fifth dynasty, which they took over and held for about 200 years. I think the people living in ancient Egypt were of a cosmopolitan mix and likely skin color was unimportant over all.

I just can't see it all being one blanket set of peoples who would then devote their art to depicting themselves with light skin and Arabic (there has got to be a better word for that) physical attributes. As we know, the common artistic trope has reddish-colored men and yellowish colored females - except for when "Nubians" are depicted when they are painted in black. Some written texts make explicit references to "Nubians" and their physicality as being different than common Egyptian norms.

I have never thought that their ancient culture nurtured prejudice about skin tone. None of the translated writing I've seen reflected any of that. So why would an entire civilization of people, over thousands of years of their history, depict themselves as physically being different than what they were? It makes no sense.

But to ask that is to spark a powder keg of anger from the modern people who espouse this "all Egyptians were Black until after Alexander the Great's invasion" view, and it is so very, very, important to those who see it that way. As a white (or as my friend now writes it "whyte") woman, I cannot see being able to engage her in discussion about the merits, or lack thereof, of her newly adopted view. So I remain silent. Especially since I am a white person and have my own prejudices to wrestle with. Maybe this is one of them in action. Perhaps this view has more academic merit than I am aware of. Perhaps someone has addressed the question I have about artistic norms. Perhaps I have missed some newer research about genomes or something. I don't know. But I feel disquieted about the theory and the danger of disputing it because of its emotional impact.