Intelligence is compression? What do you mean? Intuitively that doesn't seem right.

>What I don't understand is why LLMs haven't been able to do this yet

LLMs are just trained on what humans have said. Why is it surprising that it's still not possible to reconstruct the intelligence that wrote all that by working backwards? Think of your own work experience. When you look at a piece of code, say, are you always able to discern why the person did what they did, just from the code, with no additional context?