Nope. That’s not what I said, and the reality was quite the opposite. Humans lived in the European continent for thousands of years before the genetic mutation that contributes to European white skin existed, and it took thousands of years of European peoples traveling and mixing for that genetic mutation to become so widespread (yes, light skinned and dark skinned Europeans interacting together). They didn’t just become more and more pale as a gradient moving north. That’s not how skin works.
And again, you missed the most important point which was that without the exact pattern of migration, mutation, and evolution, there’s no stipulation for a fantasy world to adhere to ours. Especially not to such a modern perspective of ethnic segregation like the one you’re espousing. If different eye and hair color exists and is accepted without thought, then different skin color can as well.