In a world that knows no monsters, beasts, or nightmares, where the scariest thing is other people, you are the very first shapeshifter, the one and only exception.

Shapeshifters in my eyes aren't technically monsters, but oh well, I'm doing it anyway. Feel free to give me any more ideas for the very first creatures. I think you would just be boring if the only creatures that exist in this world were wild animals and humans. The creatures of this world are Orcs, elves, goblins, dwarves, humans, Pixies, and fairies. There are no monsters, there are no Boogeymen, there are no shapeshifters or undead beings. This world knows nothing of such creatures, aside from made-up stories, and even those are seen as absolutely ridiculous. This all changes with you; you are the very first, the closest thing in this world to a monster. You are a shapeshifter. What you can transform into what that looks like, and any abilities associated with it, are completely unknown. You are the exception to this world. Any creatures, beasts, and similar entities will not exist unless you choose to act as the Catalyst for their creation.