How about like how the Munchkin's card game describes humans, "They try to be, and think they are one with the <insert race here>. Of course.. they are terribly wrong."

But in essence, would deem humans the annoying trait of trying to be like other races, and fit in with them. If that means so much as interesting new ways of mimicing a meow, or gargling a growl-speak, or being able to understand bits and pieces of other languages!

Stereotypical Prydaen says "Hello, .... .... you, ... fine myself!" in prydaenese.

Or.. something to that effect, like knowing a little japanese, and trying to watch anime without the subtitles.

As I read this I thought, why not make it so when you create a human, and only a human you get to adjust your stats prior to leaving the character maker and spending TDP and you can preset 1 of the stats to have a plus 2, 1 to have a plus 1 as long as you offset these bonuses by penalities to other stats. Each human would be unique and as a race, we would be the most diverse.

Mists and Magic, Ocean Breazes, Deep Rivers Under the Sea, Trails Between the Stars: Where nothing is as it seems.