Humans are the most stubborn, enduring, and strong of the nonmagical races, but when it comes to magic, they're essentially retarded and the most even gifted among them can only barely perform even the most basic cantrips.
Because Humans don't have any magical abilities, they were driven almost extinct by magical species, and were driven to the far north in ancient times. In modern times, they hover on the brink of extinction, living in primitive xenophobic nomad tribes, barely eking out an existence in the frigid, unforgiving wastes.
They still resent the more magically gifted races for what their ancestors did, and many tribes raid southern civilizations to supplement their hunting and gathering during the cold season. Despite their magical inability, Humans are still extremely good at killing things, and many of the more civilized races fear that eventually an ambitious Human chieftain will arise and unite all tribes under one banner, forming an unstoppable horde.