You're arguing against Functionalism [0], of which I'd encourage you to at least read the Wikipedia page. Why would doing the brain's computations on pen and paper rather than on wetware lead to different outcomes? And how?

Connect your pen and paper operator to a brainless human body, and you got something indistinguishable from a regular alive human.

[0] https://en.wikipedia.org/wiki/Functionalism_%28philosophy_of...