Humans can cross between universes, posess an aurea, and can generate ectoplasms.

(According to the artist Jose Ibarrola)

The ability to make our own vitamin C.

I suppose the whole concept is meant to be allegorically similar to pedagogy, where becoming a professional character in the game world requires a guild-like training process to pass on skills from master to apprentice.
Except that longevity is not guaranteed, whereas starting out is unavoidable. :)
Yes, humanity has certainly mastered cunning, as evidenced by the spectacular acceleration of our understanding of the world around us that began in earnest with the Siècle De Lumières (French “Age of the Enlightened”) or (German) Aufklärung.
Since symbolic cognition is rare, the ability to lie is likewise; this is the main driver and source of the antidote to dogmatism, firstly as a too-successful generalization and then as a logical deconstruction, analogous to a lexical strié.

The apposite classical Greek term for this human ingenuity is δεινός (deinos) from which we get the modern English word dinosaur.
I prefer to use the Enlightenment-Romantic dichotomy, too; Elves are Romantic in the sense that they are not preoccupied with the logical colonization of nature through intellectual contrivance and gifted technology, like the Dwarves, who represent the Enlightenment perfection. Orcs are driven by the thirst for control over others, naked power qua per se.

edit: combined prior posts

The most inspiring uptake on humans I came accross was the humans in Earthdawn (kind of the fantasy Shadowrun, pen & paper RPG).

There were many races and those had vastly different and more specialized attribute profiles, while the humans were about average in regards to attributes. Since there's also (many!) classes one had to choose from that's been a major disadvantage of course: Leaves all classes as a possible option, but humans are never the best for any class.

Moreover the other races had special characteristics like night sight or whatever iirc, which further diminished the human's profile.

Now the classes had a number of skills, among them "special skills". One could learn skills that don't belong to the class (for a higher cost / on a lower level), but not the (class specific) special skills. Humans however could choose one special skill of choice upon character creation as an individual talent.

That shifted the difference to something else entirely. The other races would be allowed to be actually more powerful in physicality, in body and possibly mind. They could have keener senses or natural weapons. The advantage of humans however would be on the class side of things, in the sphere of skills. They'd have a stronger individualism with their special talent, a talent that is furthered and nurtured in learning and perfecting that skill. The others are better at pretty much everything their chosen class does (assuming class & race are aligned), but the human has that unique option to do stuff the others cannot do at all.

It's been many years ago, so I can't remember every detail. I probably misrepresent the system to a degree.

In any case it's a potentially very powerful and definitely very inspiring specialty. Moreover it makes the "boring default" the very opposite of that: Every human is unique, player designed and a daring choice.

Now that one special skill could lead to some super-powerful "combo", or it could just add some rarely useful specialty. It's kind of hard to balance and places responsibility in the player's hands at character creation. That is however precisely what makes it so inspiring! I loved it in any case.

It may be a good idea to give some default recommendation apart from the classes' special skills, like a more conservative "human default talent" option that's better on average, but won't allow fancy skill combos, so as to save new players from wrecking their builds right there.

You could go this way, rather than looking at other games, look at science fiction movies.

Take the Stargate series for example, what does that tell you about humans? They are very good at 'macgyvering' things, literally, since Macgiver is in it! lol

The best small arms
The most inventive
The best ability at finding lost items
The best diplomacy
The fastest at advancing technology

What else?

In the real world, humans have proved to be exceedingly adaptable to all kinds of environments thanks to their ingenuity.

Also, humans can be stronger and more resilient than they imagine. Physically, mentally, spiritually. It is only that most often they pray not having to find out the extent of all they can take.

Xenophobic, a serious suggestion.

Interchangeable prosthetic body parts (internal and external), that can be swapped out at will, or when they wear out or need replacing...

That honestly seems like the sort of ability that would fit cyborgs or robots better.

True, but I'm pretty sure that the human race will eventually venture down that route one day. We have (and are) already performing transplants and replacements for bones, internal organs and blood (as and when donors can be found). So why not go the next step and create the needed parts (wholesale), and make them more easily (or even user) replaceable ?.

In a game that has both cyborgs and robots as playable races, or even just one of them, this would not be a good way to differenciate humans from cyborgs/robots.

Oops!, I take all that back (and my fault for not reading your original post), as I have just realised that the topic is about humans in games, and not in real life, as I had originally thought. Please accept wholehearted apologies for the rather rude intrusion.