Settings where humans aren't 'The Mario'

[Yora]

That seems to be just him, though. He's an immortal superman, also compared to other humans.

I only read the first book, but isn't he the only human on Mars for most of the series? And do the others that show up later not gain the same powers?
As I understand it, he isn't really special (aside from being an ageless immortal for some reason), it's just that because of the low gravity of Mars all the native creatures are very flimsy. If any Martians were to visit Earth, they would be crushed by the gravity.

I'm in the preperatory steps of a couple of stories I want to write down and have been thinking about the issue of nonhumans and elves in particular (I decided to keep those as the only classic race to emphazise that it's an earlier stage of civilization than in generic fantasy settings).
For one thing, I want to occasionally highlight the exceptional human endurance. If they can get sufficient head start, even untrained humans can outrun experienced elven, beastmen, and lizardmen hunters. A second aspect of humans is that humans are one of the few races that are almost omnivores. They can eat a wider range of food than any other race and most importantly stay quite healthy if forced to improvise with their food sources. When food gets scarce in an area, humans will be the last ones to suffer from malnutrition.

Compared to other mammals, how is the human immune system? I believe to vaguely remember having heard somewhere that humans are actually quite good at coping with disease and infection.