one possible counter-argument: can you say for sure how your brain is creating those replacement words? When you replace tree with rainbow, does rainbow come to mind because of an unconscious neural mapping between both words and "forest"?
It's entirely possible that our brains are complex pattern matchers, not all that different than an LLM.
That's a good point and I agree. I'm not a neuroscientist but from what I understand the brain has an associative memory so most likely those patterns we create are associatively connected in the brain.
But I think there is a difference between having an associative memory, and having the capacity to _traverse_ that memory in working memory (conscious thinking). While any particular short sequence of thoughts will be associated in memory, we can still overcome that somewhat by thinking for a long time. I can for example iterate on the sequence in my initial post and make it novel by writing down more and more disparate concepts and deleting the concepts that are closely associated. This will in the end create a more novel sequence that is not associated in my brain I think.
I also think there is the trouble of generating and detecting novel patterns. We know for example that it's not just low probability patterns. There are billions of unique low probability sequences of patterns that have no inherent meaning, so uniqueness itself is not enough to detect them. So how does the brain decide that something is interesting? I do not know.