That's just it, LLMs are not complex, although they might be "powerful" in the sense that we've thrown more processing power at them than any human endeavor in all of history.

To an LLM a word is a unique value. It sorts unique values based on probabilities of those words appearing in sequences based on sample data. It doesn't know what red is. It doesn't know what a dog is. These are just values to it no different than the words which come before or after.

When a human being, or an animal, encounter new stimulus in various forms and context they are able to study and understand it almost instantly. They're able to solve a variation of a riddle they've never heard before, they're able to learn new things.

LLMs cannot do that. LLMs have to be retrained with data in a very specific format from the start, in essence to be remade from nothing, every time new information is added. Furthermore, their statistical approach lacks any permanence in fact, it could give a right answer 7 out of 10 times and then still continue giving the wrong answer the other 3 times, because whether "red" or "dog" was the correct value is a matter of percentages and not any understanding or contextual awareness.