If you read Genesis as opposed to brandishing it, it’s clear that there are other people beside Adam and Eve running around. The double creation story makes it clear that humans are created in multiples, and when Cain strikes out on his own, he finds other humans.

The rabbinic explanation of why we hear only about the experience of one pair, when clearly there are more, is that future nations were thereby prevented from claiming a higher lineage from others.

If you narrow down your understanding of what Genesis means to the point where any proof it didn’t happen just like in the Little Golden Bible illustrations throws you, you’re reading it wrong.