The difference between wild humans and normal humans is that wild humans still live in tribes instead of being citizens of a state or kingom. These tribes migrated from the plains of Midgard into the wild forests or mountains of Midgard or into the neighbouring wild patches of land outside Midgard. Like the desert, jungle, plains or swamp regions contested over by Asgardian and Utgardian armies. Some of these tribes have actively joined either side of the war and frequently skirmishes with convoys or armies from the opposing side.
Wild humans are tribes of hunter gatherers like the Midgardian humans of old. They are also being reduced in numbers and get increasingly more rare.