Because of chance mutatation (happens in all life forms) and natural selection. I don't want to also explain Darwin to you.
And no, natural selection also isnt a "divine process" that produces better and not so good people, or people that obviously feel better, when they are amongst themselves, or in the 'right' continent. All of that - is you giving attributes to people based on, as we now know, looks (skincolor).
Also a strawman is an argument you yourself create, to then denounce, so you look like you are winning an argument.
I never created my own argument to then denounce it. I stepped through both of your logic.
Also I'm still not likely to get convinced argumentatively by someone flipping crude race theories ("But why do they look like that?!").
Because all that argument ever comes down to, is you not liking people (in your vicinity), because they look different.
So following your logic, we should now define race, by the genetic markers for skin color?
Take a clue.
edit:
Here is what you are doing in principle. If you still want me to take time to argue with racists.
The 'obviously' is a pretty good clue.
You take a man made concept. Race. Say that it is pretty 'science' (not naming which science, btw), which in our days, sometimes can be a stand in for "divine" (== dont ask further
). Then say - because its obviously 'a thing' "I mean, look at dog races, right?" ((those large and non chance based mutations) where created through breeding focusing in on maximising certain mutations, so much higher variance in attributes), then forget that race even there is a substitute that was given to describe looks, not phenotype.
But you are making it an argument for why looks are the same as phenotype (here we are goin to the level you wanted, namely genetics). Which scientifically is wrong (looks /= phenotype).
And while phenotype never ever was equaling race in human history. And still isnt today.
Why you do that is, because you want an attribution for looks = 'behavior' so badly it hurts. But you cant say that openly, so you now need a helper construction, which is historically positively loaded (when you are talking about your own) which is tribe. Which later became race, btw mostly through the nation concept (as tribes grew bigger (learned how to sustain bigger tribe sizes)).
Darwin came after that, and just also used the word. So he is also not the origin of this 'divine authority figure' concept you are looking for to make it 'obviously' something.
That 'divine' concept for you mostly lies in culture (shared stories), btw. And it is also a clue how race as a concept was originally formed (language, and later PR).
Now lets say you successfully can make the argument that phenotype = race, which you cant - but colloquially - maybe.
Thats the best you ever can get to. All the other concepts. For why people of the same human race have the same phenotype (what about bloodtypes? In Japan there are cultural stories, that bloodtype is very important as an indicator for behavior - thats also just a shared story, you know?) and therefor likes/preferences, or behavior patterns, or cultural preferences are so obviously wrong it hurts. But thats also what you are mainly flogging ideologically. Thats already insanity and not wanted by mainstream culture today, for very obvious reasons. (How about air travel is a thing?) And if you then jump from that to 'well certain races obviously feel more relaxed in their motherland' thats so many steps removed from how reality, or even genetics/natural selection works (mutations over multiple decades), that the closest approximation to that argument is something like - "well obviously humans dont feel well, while driving in trains, because it is much faster, than they were supposed to move (genetically?)".
And if you want to do the same with skin pigment and sun intensity - let me just tell you that things like jackets and airconditioning do exist. And people dont have to wait for multiple generations and chance mutations to 'feel better' in Hawaii.
So if the main concept of that divine'/higher value concept, that you are looking for with that "well obviously this race...:" is cultural (comes from shared stories (first language, then PR)), then dont say it is looks - that translate into behavior - that translates into group preferences - and ultimately preferred region to live in for that race in the world.
Because every single jump there is voluntary and not proven by something like science at all. Someone just said it.