If you try to combine creation myths with anthropology, which doesn’t really work but bear with me, both God and Satan should be black people. In the bible, man was made in God’s image. The angels probably looked a lot like God, too, but it doesn’t really say (Satan being a former angel). The first modern humans came from Africa and migrated outward to settle the rest of the world. The settlement of northern Europe happened several tens of thousands of years after human migration began. Later still, people began to have pale skin to better absorb the weaker sunlight there. The existence of white people is a relatively recent development in human history. When God created early man in his image, they didn’t even exist yet.
So, white Satan is feasible but unlikely, but God is almost definitely a black person. Jesus was probably a middle eastern dude but that hasn’t stopped painters from portraying him as a white guy for hundreds of years. So in reality, it probably just depends on who you ask.