DEMIHUMANS, THE XP "CAP", and what it means to be HUMAN

I've always hated the idea that demihumans can only reach a certain XP level, esp given their longer lives. Sure, they get nifty abilities like "determine approx depth underground", but is it worth grinding to a halt in all other areas around lvl 8?
My solution when designing "Player Species" for Gnarth was to allow unlimited advancement for all, regardless of Class. But what about the Humans? What makes them "special"? Like everything else on Gnarth, I took a cue from pulpy sci-fi romance and adventure media; The Human Protagonist is always quite adept at Adapting, picks up the necessary skills relevant to the Alien World Quickly, seems extraordinarily Lucky, and proves surprisingly Difficult to Kill! In game terms: Humans receive +10% earned XP, have +1 to all Saves, and add +1HP/lvl to rolled HP. No extraordinary, specific ABILITIES like "Infravision", but rather a few generalized, broadly useful EDGEs!