"An LLM predicts the next word based on all the words before it. That is the whole story. There is no idea sitting underneath. The words are everything."
This is just flat out wrong.
Words are used as training data, to build a system of vector embeddings. The LLM contains no words. That was the training data long discarded.
Vector embeddings are groupings of meanings derived from the relationship between the words in its training data. This entire system is modelled after human neural mechanisms in a way that machines can emulate.
"But your brain works the other way around. First there is a concept, a feeling, an image, and then the words come out to describe it. (At least, this is how I feel my own brain working.) For us, words are the byproduct of consciousness."
It's working the same way around (you are not saying Ai has consciousness that is derived from words!). And you make a huge jump from the concept that 'words come from concepts' to 'words are the byproduct of consciousness'. Because 'concepts' are not equal to 'consciousness'.
In fact you do not define consciousness at all, making it hard to determine what argument you are actually making at all. You seem to think humans have this trait of 'consciousness' but can't explain or evidence it beyond 'feeling it'.
Consciousness it defined by many as the ability to experience events and process thoughts or qualia. It's hard to test this, and we can see why that is with an AI - it may claim to be conscious, or even claim not to be, but how can we trust either answer? Philosophers aren't even sure to trust another human who claims to be conscious, and we struggle constantly to determine at what point creatures the animal kingdom are conscious or not. Cats? Lobsters? Snails? or even across the plants?
Before you can refute the consciousness of AI, first establish the consciousness of humans. A better question to ask is what does the uncanny emergent ability of an AI to mimic a human say about consciousness?