There’s not a hard-coded wiring diagram of how the neurons from the brain connect to the rest of the body—everybody’s wired a bit differently, and the brain normally figures out how to work with what it’s got during development. So there’s no one-to-one way to connect the nerves from one person’s brain to those in another person’s body—and if it doesn’t get the signals it’s expecting, it will just seem like noise.

Besides which—if I remember correctly, you can’t generally reconnect severed nerves. Instead, the remaining portion of the nerve cell has to grow a new axon that retraces the route of the old one, and it can only trace the old path for a limited distance (like, if it’s close enough to receive chemical signals from the original site). But I’m not sure I’ve got all the details right on that.