Humans are the dominant racial group on the Continent, forming the majority of inhabitants in both the Northern Kingdoms and the Empire of Nilfgaard. When they first arrived on the already populated continent, they rather quickly set about conquering the lands already inhabited by elder races. This led to their dominance and so the elves, dwarves, gnomes and halflings are now generally referred to as nonhumans.
Hailing from a destroyed world, humans first appeared in this world after the Conjunction of the Spheres. The Dauk and Wozgor peoples settled on the Continent long before the First Landing of humans belonging to Nordling culture. Scholars speculate that the Empire's native inhabitants hail from a human culture predating those dominant in the North.
Humans and elves are not terribly dissimilar in appearance. Roughly sharing a similar size, elves have pointed ears, smaller teeth and tend to be more delicately featured. Humans also do not live as long (by far) as elves. Of note, since both humans and elves can easily interbreed, most humans today are believed to have elven ancestors.
The humans are at war with elves in particular and have a rather poor relationship with the dwarves, halflings and gnomes. The races do live together in the cities, however the non-humans are forced to pay a levy just for being non-humans. Several pogroms have taken place in the cities. Many of the larger human cities were built on the ruins of elven cities which the humans had burned down; cities like Vizima and Novigrad, to name only two.