You may have found all of the 'base' versions of the various creatures out there. For example, you've seen Deathclaws, maybe a Radscorpion, Mirelurks, Mole Rats, Bloatflies, maybe Stingwings and the blood svcker insects. You've probably also seen ghouls and humans, and maybe you've seen super mutants and synths (I encountered my first mutants and synths at level 17). Similarly, you've probably seen Mister Handies and Protectrons. I doubt you've seen Sentry Bots or Assaultrons, or many of the highly varied selection of all the previous creatures (a low-level Deathclaw is not the same creature as a high-level Deathclaw, either in abilities or in model).

Maybe

But the game is great and goes on for a lot longer