It's not just "fiction," it's fantasy. That seems to be the bit that's being overlooked the most, or, at best, looked at, but through nothing but a very modern, scientific, lens. Orks and trolls and elves and dwarves are just different from humans, period, paragraph, full stop. They live longer or shorter, they're bigger or smaller, they see in the dark or see heat signatures, they gestate children for different periods of time, have different teeth, have horns, all kinds of crazy stuff.
Worrying about it being "racist" for them to also have mental differences, not just immediately obvious physical ones, strikes me as rather hypocritical and, more importantly, largely missing the point of fantasy metahuman races in the first place.