>>52189
This is actually something that I've encountered myself in a lot of settings, and something that interesting enough, has "canon" rules, depending on the system.
To some extent established lore literally says that the gods for some races literally will not allow interbreeding between certain races, but humans are almost always allowed. For instance, as far as most D&D settings are concerned there are no ork/elf hybrids because the goddess literally will not allow it. But the god overseeing humans doesn't give a fuck. Make whatever hybridized abominations you want, even if it kills you.

In at least one interesting twist, there was a concept for a setting where orc + elf = human.