Our writings are a complete fingerprint of the thought process, because we are able to pick up any thought process from a book, without ever seeing or otherwise having contact with the author

That doesn't follow, even a simple encryption program can make that possible without an intermediate actor being able to crack that.

Humans all run very similar software/hardware so we can read what each others write, but so far the computer isn't close to the same behind the scenes thoughts. Meaning all the things we humans leave out when we write are actually important, so the text isn't everything.