I'm A Banana
Potassium-Rich
There's two major camps.
The first is that monsters are monsters, not people, and thus are supernatural entities inherently, capable of being born of wickedness and corruption itself, and thus they can be monolithic and need little variety. An orc is not a natural thing -- it is a manifestation of rage and a scourge on the land. Lets call this the "mythic" motif.
The second is that monsters are creatures, just potentially dangerous creatures. An orc is a person, and so has free will, and can choose to be other than what it is. Lets call this the "modern" motif.
Both are valid and cool, but D&D has long leaned more toward the latter than the former -- ecology writeups for your mind flayers will do that.
The first is that monsters are monsters, not people, and thus are supernatural entities inherently, capable of being born of wickedness and corruption itself, and thus they can be monolithic and need little variety. An orc is not a natural thing -- it is a manifestation of rage and a scourge on the land. Lets call this the "mythic" motif.
The second is that monsters are creatures, just potentially dangerous creatures. An orc is a person, and so has free will, and can choose to be other than what it is. Lets call this the "modern" motif.
Both are valid and cool, but D&D has long leaned more toward the latter than the former -- ecology writeups for your mind flayers will do that.