Well, close. The main room has the following pieces of decor, every single one on a different depth, from furthest away to closest to the player:
- Stars and the moon (stationary)
- Wall with large windows
- Scaffolds with stairs in between
- "Scaffolds" hanging from the ceiling
- Crates on the floor
- Diagonal support bars
- More "scaffolds"(?) hanging from the ceiling
- More crates on the floor
- Vertical support bars
- Lamps and chains hanging from the ceiling
- More diagonal support bars
- More lamps and hooks hanging from the ceiling
* Layer with the player where the actual game takes place
That's 12 in the background (not counting the player), although technically the mountains you see in the intro are still present, but I don't think you can actually see them anywhere through the windows in that room. If you count those, that'd be 14 differently moving parts of background.