It’s obvious the earth had other humans. Cain married one. The issue is from the Hebrew perspective, not from the already existing populations. The migrations were a seeding of the Hebrews amount the tribes of men. And one could suggest breeding higher IQ’s among the ‘cave dwellers’. The Jews play the pivotal role. Always have. Always will. Your thinking in concert with the prevailing ignorance (that seems logical) is why so many are blind to reality. Evolution comes to mind. Theory. Like the Big Bang, no one will ever get behind it to see how it occurred.