Egyptians weren't black, you might as well say Moses was black.
There was a Nubian Dynasty however there were other dynasties as well, the closest thing to ancient Egyptians are the copts, this is afrocentrist propaganda.
Arabs don't descend from them either but there are two different meanings of Arabs, there are "ethnic" Arabs" and there are cultural "Arabs", the people who were Arabized were the Berbers in North Africa, the Levantine peoples, and the Sumerians, the real Arabs descend from Saudi Arabia and forcefully dominated the populations they invaded, think of it like Latin America, you had Spaniards who invaded South America and raped and mixed with the population creating mestizos and now they speak Spanish, follow Catholicism and Spanish tradition.
I see it the same in the Middle East.