I don't think fantasy writers play enough with the concept of the different fantasy races having distinct ethnicities. Like imagine a group of mixed peoples, where the dwarves are all roasting each other like dwarves do, and one of them remarks that when he first saw one of the other dwarves in the group, he mistook her for a man. The other dwarves in the group blink in surprise - the closest that dwarves will go to an audible gasp of shock - and she pulls out a knife and tries to stab him.
Once the dwarves have been separated from each other and the situation has calmed, one of the humans asks another dwarf what that incident was about. Naturally a human woman would have been insulted too, but dwarves are so jovial about insulting each other, why was this matter different?
And the dwarf who was asked explains that there are things you can brutally insult another dwarf about, and there are things you simply do not touch. The dwarf-woman in question is from a completely different region of The Great Underground as the others, and her people have different norms about what kind of patterns men and women braid into their beards. The dwarf insulting her wasn't only insulting her appearance, he was being racist.
The human is surprised to learn that dwarves have different peoples, and the dwarf looks at them like at an idiot. Of course they do, they even look completely different from each other. And the human listens as the dwarf lists off various distinguishing clothing details too nuanced for a human to notice, and then how dwarves coming from different corners of the world have different physical traits, according to what kind of conditions their local stone types dictate.
The human spots a connection and goes oh! We have that too, though ours are not about rock types and tunnel air, but the weather aboveground. Humans' facial features vary by how hot, cold, arid or windy their ancestors' homelands were, and our skin tone varies by how much the sun shines in their native region.
The dwarf frowns at the last part, going "I thought you people just paint your skin and dye your hair for fun", and the human admits that yeah, we do that too, but not all the time, and not the whole skin. The dwarf asks, what of that tall woman the colour of dravite, her palms and the soles of her feet were lighter than the rest of her. Does that mean she paints herself dark to be more beautiful?
The human says no, that just happens naturally. Maybe it's because one's palms and feet aren't exposed to the sun as much, so they are paler.
The dwarf nods, still unsure whether this is actually legit or just the human habit of lying for fun, and proceeds to ask about the wild northman of their party. He is as pale as an olm, but the palms of his hands and the soles of his feet are dark. Are they painted, or naturally that way?
No, the human answers. That guy just doesn't bathe.
