In humans it is many things, but primarily a life support system for that continuous chain of chemical reactions. To continue that chain you have to so some particular things, like keep it from getting too hot, or too cold. Keep it fed and watered. Keep it from getting injured, which is the job of our sensory systems. Those are the baseline things we see in animals.

In humans, at least until recently we had little to no means to extend our body beyond our original biological constraints. But now imagine I put a wireless sensor on your arm feeding into the nerves on your skin. On the otherside was a 'wireless' hand, we'll ignore if its biological or artificial on the other side, and it feeds back data to your implant so you can feel remotely. You'd still consider that 'feeling' right?

But now lets take it up a step, instead of feeding back to your skin, feed those wireless impulses directly to your brain. The same interpretation is still happening. External impulses (data) are being fed back to your body for interpretation and processing.

Depending on how LLMs scale in the future, our idea of embodiment may have to change. With a significant enough sensor network, an AI could embody a planet.