Monkeys are smarter than bears -> not racist
Wookiees are stronger than Ewoks -> not racist.
Elves are more agile than Orcs -> still not racist.
Chinese are smarter than Kenyans -> hella racict.
(It truly pained me to write that last line. It felt bad to do it even as an example. Yet some people think that this is somehow fine. Boggles my mind.)
I'm not going to butt my nose in your argument. But...
You do see what you did there, right?
Monkeys and bears are different species.
Wookies and ewoks are different species.
Elves and orcs are different species.
Chinese and Kenyans are
not different species. They are the same - humans.
And I hate to bring this up. I really do. But maybe it'll allow the framework of the argument to shift a little.
In D&D, at least most of the lore I have read, there is not a lot of melting pots. Thus, not a lot of cross-pollination of ideas. There is no internet. Not all cultures have access to the same learning. Maybe some struggle to have access to food. It's hard to build a culture of book worms when you're worried about competing with all manner of crazy beasts for your slim next meal. It's easier to create a culture of toughened individuals that know how to fight when you are forced to fight each day just to get some berries or go on a hunt.
So if you do culture ASI's or bonuses or skills or whatever, you could easily have different cultures within the same species (It's been mentioned many times in this thread). Most of culture is based on natural resources and environment/terrain anyway. From the musical instruments to the food to the traditions.