WHY does the non-aggression principle apply? And why is intellectual work supposedly not protected by this principle?
Because murder is a form of aggression and copying information isn't.
WHY do you own yourself?
I have the best claim to my body. Everyone else is a latecomer with respect to me and my body.
Here you are explicitly denying the existence of information
No, I'm not. I'm denying that it's a form of property. If you write in a book you own, you still own the book and the writings, the physical copy itself, not the information contained therein.