ManaSeed is right.
Battle Brothers is the kind of dark fantasy where exotic fantastical elements are generally dangerous and horrible. If there are elves, they are probably sadistic monsters that lurk in the deep forests and murder woodsmen. Any short underground people are probably jerks who torment miners similarly. Vampires have an irresistible need to eat people to death.
Magicians and nonhumans aren’t mercenary material. This reflects bad attitudes from real life, but the game is what it is.