Actual researches returns unequivocal no as far as LLMs being anything like our brain or a language model (worth googling for research how NNs are un-able to simulate any functionality of actual brain). In fact, even the NN concept as such is a pretty much a failure as an analogy to the brain. NN was in fact (many have argued) a marketing term more than anything.
Of cause, the underlying phenomenology is worth to question/investigate and research further, in both domains (NN and human learning). The failure of NN analogy to the brain, I would argue, is the same as failure of todays (hyped and false) analogy of CO2 as a greenhouse gas. Nature generally does not optimize as humans to a single metric or a variable. On the contrary, collectively, nature seem to be more concerned with stability/robustness than any individual or a single group fitness. That statements would take too long to unpack, but I take it a better model to start with...(some researches already had began of a decade or so).