That’s not a statue of a slave. Only a Pharoah could wear that headress with the cobra on it, because it’s a symbol of the Pharaoh’s authority (like a crown). He is also holding the rod and scepter of a Pharoah, and it looks like the base of the statue has heiroglyphs enclosed in a cartouche, which was only done for the names of Pharoahs.
Egyptians routinely carved statues out of all manner of stone, it was not necessarily used to depict the skin color of the person they were portraying.