I'm not following you here, you seem to be conflating LLMs ability of language use with the brain's ability of thinking and cognition?

Are you saying that thinking and cognition requires language use? Cause I think not.

Or are you saying that language use is sufficient for cognition and thinking? Cause I'm also not convinced of that.

What I am convinced of, is that a machine capable of language use is capable of tricking people into believing there's a "there", there. In pretty much the same way as the famous supra-normal stimuli experiment made baby seagulls believe that a stick with a red dot was their parent. It's exploiting our instincts.