Human

Biology
Humans in Grimgar are much like (if not the same) as Humans from our world, the main difference is that they're closely biologically related to most humanoid races in grimgar, they can interbreed with orcs, elves and dwarves at the minimum, as has been shown through Jessie Land and Jessie Smiths explanation on their offspring.

Humans are physically superior to most goblins but inferior to Orcs, mentally there seems to be little difference in their capabilities.

Culture
Human culture isn't touched upon much, as much of the story is seen through the eyes of a group of less than able outsiders who spend much of their time out on missions, and away from town. Still, human society is ruled by a king and his nobility. The use gold, silver, and copper coins as a trade medium, and worship various gods, usually in exchange for power. They are considered powerful and aggressive, having once ruled the entirety of Grimgar's known world prior to the No-Life King, and during the events of the story are seeking to reclaim that rulership. Humans are apparently somewhat xenophobic, tolerant of foreign humans, and human-like races such as dwarves and elves, but not of Orcs, Goblins, Kobolds, or other less human like races. Humans are likely also the most organized, as part of the No-Life King's assault started with establishing structure to the different races that they didn't have before.

History
Humans previously dominated Grimgar but were defeated by the No-life king who united orcs, undead, goblins etc together to overthrow their oppressors, the no-life king implemented important fundamental structure to the different races, giving them much needed leadership and hierarchy. The other races rising up was due to the mistreatment humans had given them in the past seeing them as inferior beings, even though we have seen that most of these races having the same capabilities as Humans if not better. This led to humans fleeing to beyond the tenryu mountains in the south, called the Arabakia Kingdom.

Beyond the Mountains is referred to as the "frontier" where most of the story takes place, Humans used to live in the kingdoms of Arabakia, Ishmal, and Nananka (which resided in the frontier) before the No-Life King destroyed the Ismahl and Nananka kingdoms.