This may be too detailed as well, but ... should we start with general "classes" of beasts? For example:
1. Ambient creature - This class is decorative. Player interaction may only consist of the ability to scatter small groups. They cannot be killed (maybe?) or harvested. Birds, fish, bugs, frogs, floating airborne jellyfish, tribes of tiny, living, fungus people, etc.
2. Hostile creature - This class is a nuisance or barrier to the player. They are hostile to player contact either based on an aggro threshold (provoked level, radius, or line of sight). It serves to annoy the player or attempt to kill the player. These may exist alone or in packs. Sharks, lions, wolves, radioactive pigmy trolls, ghosts, zombies, etc. Perhaps some only spawn at night or during certain time periods.
3. Domestic Resource - This class of creature can be "used" by the player. Farm animals or game animals. Cows, pigs, chickens, deer. Tofurkeys ... for the vegetarians. Sentient tofu with "plumage" would be hilarious. Harvesting may vary based on the player's chosen culture (spirit energy vs. meat; milk/eggs vs. meat).
4. Domestic Pets - This class of creature could follow the player around. Fetch items, or act as protection for the player, or just as a "companion". Dogs, cats, flying gerbils (flurbils).
I don't think we're considering creatures for transportation right? No riding on horses or dragon backs? If so, maybe another Domestic-Transport category.