Why we humans look so different across the world?

Skin color is an adaptation to environment. As humans started migrating north, their skin turned paler. As the migrational path extended south again, the skin turned darker once more. Eye and hair color are random mutations. If the trait is considered beautiful and does not hinder survival, it will be passed on to the next generation (sexual selection). Neanderthals did have blue eyes and ginger hair. BUT we did not get those modern traits from them. We got them through random mutations.