I think you’re conflating intelligence and consciousness. Pain and suffering requires consciousness but intelligence does not imply pain or suffering or happiness. LLMs are already “intelligent” to a certain degree in some aspects, though not generally intelligent like humans. But there is no reason to believe that you couldn’t have a generally intelligent artificial agent that lacks consciousness and thus can feel no pain or suffering.

That’s true, but that doesn’t contradict the above comment. Unless you believe in something like a spirit or soul, you must concede that human intelligence ultimately arises from physical matter (whatever your model of physics is). From what we know of science right now, there are no direct reasons for thinking that true intelligence or even consciousness is limited to biological organisms based on carbon and could not arise in silicon.