Human brains are objectively and quantifiably vastly more complex, including context and planning, they don't sequentially predict the next word.

Prime example of a human brain being architecturally different to an LLM: LLMs never interrupt themselves. They never get mid-sentence then say "actually, scratch that, I was wrong" or "now that I've thought about it, this is actually a better method to convey what I was trying to tell you".

There's a lot of material on this exact topic highlighting how the human brain does not have a transformer architecture.

Anecdata: I don't think in words. I think in abstract non-concrete thoughts. Language is what I use to convey my thoughts to others, program, or write notes to recall those abstract thoughts. However, I am also autistic, so take that with a large pinch of salt.