Neurology is full of very uncomfortable facts. Here's one for you: there are patients who believe their arm is gone even though it's still there. When the doctor asks whose arm that is, they reply it must be someone else's. The brain can simply refuse to know something, and will adopt whatever delusions and contortions are necessary. Which of course leads to the realization that there could be things we're all incapable of knowing. There could be things right in front of our faces we simply refuse to perceive and we'd never know it.
Famously, our nose is literally right in front of our faces and the brain simply "post-processes" it out of the view.
After breaking my arm, split in two, pinching the nerve and making me unable to move it for about a year, I still feel as if the arm is "someone else's", as if I am moving an object in VR, not something which is "me" or "mine".
Oliver Sacks' A Leg To Stand On is a lengthy discussion of that, including his own experiences after breaking a leg---IIRC, at one point after surgery but before he starts physical therapy, he wakes up convinced that a medical student has played a prank by removing his leg and attaching one from a cadaver, or at least sticking a cadaver's leg under his blanket. (ISTR he tries to throw it out of bed and ends up on the floor.)
