Despite common belief I think the answer is no Springtrap is not a dead body inside a suit Afton is very much alive in there.
First of all it’s important to remember Springtrap does in universe have bones and organs though they were not modeled because Scott didn’t think anyone would see them and he can’t model human anatomy (I don’t remember where this came from but this was forwarded to me by Tato a long time ago). Scraptrap did have bones though and “lungs” though they have bone textures so I’m not sure if we can actually call them that. If we want a more accurate description of what Springtrap canonically looks like look no further than the Twisted Ones.
This is important because Springtrap canonically needs these to function as a living being.
Another thing to remember is if William had actually died on that faithful rainy night that by the night FNAF 3 takes place there would be nothing left of him. Bones take around 30 years to decay (according to a Dawko video from before FNAF 3 released) and not only does Springtrap canonically have bones but he has plenty of flesh too which means that he didn’t rot the amount that he realistically would. This is also pointed out in The Twisted Ones. The room he was in also lacks the conditions to preserve the body.
His voice also supports my theory. When characters possess animatronics their voice is not preserved unless the animatronic has no voice box they have the voice of the character they possess. We can assume that Spring Bonnie had a voice box but Springtrap/Scraptrap sound like Afton still. I’m fact his voice sounds like a more damaged Afton it’s very gravelly. We also hear him sigh multiple times in AR which kind of sort of need working lungs to do. Though this would seem impossible if the books are to believed but that is not the case. It is explained by William in The Silver Eyes that getting springlocked will case your vocal cords to be severed but shortly after this is explained he reveals that he knows this because he was already springlocked and survived…if you don’t see the problem with that let me phrase it like this…he said his vocal cords were severed, if you got no functional vocal cords you can’t talk. So that might’ve literally been a lie from Afton or it at least isn’t as bad as he described just damaging them instead of destroying them. This is further proved in The Twisted Ones and Fourth Closet where even after his springlock failure he still as much if not more of a chatter box. So Springtrap/Scraptrap still has functional vocal cord, human vocal cords and is not speaking with a voice box.
His eyes are also human BTW and can still move.
The final nail in the coffin for me is we can literally hear his breathing and heart beat. His FNAF 3 he makes some sort of sound that I think sounds like some sort of breathing take listen, https://youtu.be/Qg7FDuhhB7E?si=auahdKSBixl_deCa
Like I said earlier he also sighs a lot in AR and his lines are also pretty breathy at times. So he breathes and I’m. pretty sure that dead people don’t do that. His heart beat is also audible in FNAF 6 (barely in game but when turned up it’s very clear) take a listen for yourself. https://youtu.be/m3XxdMQiFzY?si=3JeaXI5CkR5RutE2
The names on screen are presumably what they’re called in the files so just in case you weren’t sure they’re literally labeled as heart beats. His heart still beats dead people definitely don’t have functioning hearts. AFTON IS STILL ALIVE IN THE SUIT. (+He is confirmed alive in The Fourth Closest and The Man what ever room he was in).
So Afton is NOT dead in Springtrap/Scraptrap he is very much alive and probably suffering. So just remember that now.
But what do you think if you agree mind helping me come up with a logical way he survived having his body pierced from all ends with endoskeleton parts.
And a final question to think about if he’s alive what did he eat while in the safe room and how he…relieves himself?
