Nobody knows what they are saying either, the brain is just (some form) of a neural net that produces output which we claim as our own. In fact most people go their entire life without noticing this. The words I am typing right now are just as mysterious to me as the words that pop on screen when an LLM is outputting.

I feel confident enough to disregard duelists (people who believe in brain magic), that it only leaves a neural net architecture as the explanation for intelligence, and the only two tools that that neural net can have is deterministic and random processes. The same ingredients that all software/hardware has to work with.