Hm.... *ponders*
Well, It is my honest opinion that the Human Race is, comparatively, supposed to be a touch boring. However, is it indeed quite true that it is rather ridiculous for them to be as sub-par as they seem to be. Keeping that in mind, I would like to suggest the following, using the forumula of 7 being a lucky number for Humans:
Humans learn an extra 7% faster on weapons skills and attributes. Chances to increase stats in skills/traits are upped by a modest 7%. In effect, a Human's ability to learn anything is upped by a mere, humble, 7 percent. 10% seems a bit much to me, as the cup starmonth gives you an additional 10% chance for a lot of stuff. Meanwhile, 5%, a nice little number, feels too small to be even signifigant to be noticed, to where we may as well ignore the increase to begin with. so the number 7 seems a fair percentage in my personal opinion. I don't play humans too much, but usually because I happen to let (f)ate decide. Given that, I sometimes will specifically choose humans because they are the Marios of ADOM: Classic, well rounded, and able to be anything.
So yeah, to reflect their adaptability and versatility, I say we give them a boost to being able to learn anything learnable by 7%