[FULL GAME SPOILERS] Who were the Monsters?

[Kein]

I don't think every monster is supposed to be a person (that gets mentioned in the game).

Nr1 is most likely the UH roboter you encounter in the very beginning (the one that breaks out of the room after you datamined the other UH roboter) since you can encounter the monster in the very same area moments afterwards in the omnitool room if you don't hesitate to open the seal/door.

You are forgetting that monster does not have to be a hybrid (mutant ) or have human body TO have personality/consciousness.

Someone completely missed out what SOMA was about?