Blacks have nothing to do with Cain. The curse of Cain is to be a wanderer and to not be able to till the ground.
The Egyptians claimed their Pharaohs ruled for tens of thousands of years, but we know that is not true. Nearly every pagan culture claims an impossibly long history, and they also usually claim to have always lived in the land they are in now, despite the fact that we know they migrated from elsewhere. Those writers were simply not very reliable.
There's plenty of evidence for artifacts of certain cultures going farther back than 2350BC, way farther.
If you are claiming there were others saved besides the eight on the Ark, then they couldn’t have souls, so they couldn’t be men. So what are you saying exactly? That some other races look human but do not have human souls?
They had souls. Rightly divide the Word, the bible is the story of Adam's family and those who came in contact with them. Since the crucifixion, all who believe in Christ are part of Adam's family.
But if you don’t, you are subhuman? Is that it?
There are no subhumans.
“There’s plenty of evidence for artifacts of certain cultures going farther back than 2350BC, way farther.”
Well, you go ahead and believe your interpretation of that evidence, and I will believe the Word of God. Someday, we will know which is right.
“They had souls.”
Not according to the verse I quoted. Only eight souls survived the flood, so if you say others survived, they could not have had souls, unless you want to call God a liar.