In lore Explanation
The main dwellers of hell, they are what humans would call "Demons".
Unlike what the human name would suggest, they aren't actually demons(That would be a different creature), they are more like the humans of Hell, adapted to heat by way of increased body temperature, and tough, fire-proof skin.
Just like humans, they have a society, cities, kings, queens, and frequently war with the other tribes.
Out of Lore Explanation
uhhhh they're just hell humans bro