a machine, in typical usage, is an object designed and constructed by a deliberative intelligence for a purpose, which is what evolutionary theory states living beings aren't
the machines we currently conceive and manufacture also lack many structural features common to biology
in biology a single component may have many functions, some of which may interfere constructively or destructively, while in engineering it is often considered best practice for each part to do one thing
organisms self heal, subsist on/in an ecology of other organisms, and are resilient to informational errors
forms of computation resilient to bit level errors could be said to mimic biological antifragility, but they run on an extremely fragile physical substrate which requires constant tending (by organisms) to keep entropy at bay
even if our implements were as autonomous and resilient as we are, it still feels valuable to preserve a clear distinction between objects, which all agree may be understood solely as a means to an end, and subjects, who (in kantian form) are ends in themselves
this is not to say designed objects could not in principle become subjects, but to claim e.g. there is a clear path to sentience for deep learning models is for now speculative at best, and until we have good reason to believe a tool may develop subjective experience it can be a dangerous thing to personify it, and in any case we ought not compress ourselves into its image
There may be a part of the brain that is modelled well by an LLM, but if so, there seem to also be parts that aren’t, or even existing “multimodal” models like GPT-4, which is more than an LLM.
Humans, including their brains (both in the narrow sense and in the broader sense of “everything that contributes to cognition”, which may extend beyond the brain proper) are machines, and their function probably will, someday, be mimicked by machines. But they are still more complex machines that modern “AI” systems