"Mortalkind" was a term used to describe a variety of creatures that shared common features. There was no exact definition or qualification of who was considered to be mortalkind, beyond that they somewhat resembled the giants of old. Most typically stood between two to eight feet tall and possessed two arms, two legs, and walked upright. They varied widely in terms of size, lifespan, and features, and were generally capable of using tools and weapons. Some had innate Spellcasting abilities, though this was generally an uncommon trait.
Mortalkind were further defined by their sapience and intelligence, though this also varied widely; there was no exact qualifier for what were considered "intelligent", as many creatures possessed acuity equal to that of humanoids and goblinoids. In general, however, these creatures tended to think alike. Even Crowfolk who lacked creativity or Lizardfolk who possessed an "alien" logic still shared some similar understandings of the world, at least when compared to the network intelligence of Myconids or the divine insights of Angels and Devils.
Many Elf and Dwarf scholars, typically of older lineages, referred to the concept of mortalkind as the "free peoples" or as "smallfolk"; a term defined by the larger Giant-kin who ruled the Head of the Greatwyrm in the Age of Giants. Most Human scholars considered the vast majority of smallfolk to be "humanoid", including Crossborn and Otherborn, which other lineages took exception to. In this view, major exception to "humanoids" were the "goblinoid" lineage, such as Goblins, Hobgoblins, and Bobgoblins; however, this distinction was more colloquial than scientific.
More in-depth information on the smallfolk of Somnum can be found here.