I mostly agree with you. And I commend your principles.
Some of your examples need improving is all I'll say.
Like sending a white guy to the equator for a decade. Okay fine, they go dark skinned. But bring him back up north and he is white again. Send a super dark skinned guy far north and he will get somewhat paler, so it works both ways. But they retain that difference because they are different.
We have developed differences mostly based on our origin in the world, be it Asian, African, Egyptian, Indian, etc, but we are such an internationally mixed people the differences are meaningless.