First, I consider anyone who meets the classification of homo sapien human. If something happened to their mind, even if they are in a vegetative state, they are still human.
Second, I don't think it's too broad to say any random thought or thoughtform in your head isn't human. I don't know if the thoughts an octopus has can even be compared to human thought. Octopuses are extremely intelligent creatures, but they may not think remotely the same way we do. Maybe the concept thoughtforms or language make no sense to an octopus, and they know concepts we don't even know exist.
Third, even though we have less sentient parts (like the cells of our body), I don't think it makes them inhuman. I doubt your hand will protest for free will anytime soon, even if you made a hand thoughtform it's something else telling your hand what to do, not your hand giving orders.
The human body can experience human experience but a host/tulpa can't? I assume all experience is being perceived by whoever is directing the body