Basically, without the reskins, its:
Molerats
Dogs
Radscorpions
Protectron/Sentry Bot/Turret/Bigger Turret/Mister Gutsy/Robobrain
Mirelurks
Mirelurk Kings
Fire ants
Super Mutants
Human enemies
Deathclaws
Bloatfly
Yao Goai
Feral Ghouls
For an RPG, this isn't enough. Not to mention they really all attack either with melee or various ranged weapons, so it still gets repetitive.