Humans are one of the species endemic to the Fadelands. They originated in Verandi, but spread out to the three Brother Nations under the leadership of The Smith, who transformed humanity from living in isolated villages to essentially adopting the feudal system.
By the time of the campaign, most humans live in Vistria or Laric, with small populations in Korstraad (mostly either Vistrian farmers or nomadic tribesmen) and Tarq. There are also humans in the Shadowfel, but we have next to no information on them. At one point there was a village of them in the Underdark, from which a certain individual hailed.