IS SIMON A ROBOT?

[cantremember]

I'm not far into the game, people have already figured it out no doubt but it's my understanding Simon is a robot, and his personality/conciousness/AI/... doesn't allow him to realize that. The wrangler was also convinced he was human and could see his feet and hands, even though he didn't even have any. Simon just slowly became aware of it as he realized he could breathe underwater and had a flashlight etc.

Still I don't get: there seem to be 3 types of robots:
- Purely mechanical robots (the broken down robot in comm center, Catherine, the mechanical fish)
- Mechanical robots enhanced in structure gel (the first enemy in the geothermal plant and the broken down robot just before)
- Humans deformed by structure gel (The guy you hear dying at the start, grabbed by tentacles in the wall, Amy attached to the wall with tubes in her, the enemy that can teleport)

Are there any differences in their creation or purpose?
Also why are the robots hostile to you? The wrangler robot seems to think you're human, though he says you look like a diver. The other robots think they are human and see you as a robot and want to kill you?

And what kind of robot are you, a deformed human ? Perhaps a corpse that was laying in the pilot seat, and the AUW mechanized the corpse and implanted some random brainscan that it happened to be in possession of?