Oh, for God's sake. Someone's feeling cynical.
This is not how humans are portrayed in the SC2 universe, anyway. The human society of the future is much more peaceful and rational than the nations of today, and even at our worst we aren't as bad as many of the fictional races portrayed in the game. It shows as much lack of imagination to claim that human beings are the worst possible race in the universe as to claim they are the best.
And why does everyone pick on the last 2000 years? Human beings have been fighting for much longer than that. Is this some misguided attempt to blame Christianity in particular for the bad things of the world, or something?