If an LLM matches the distribution of text, it might superficially make similar mistakes a human would: introducing a typo that might be common on a phone keyboard. If asked, its reasoning will likely be that the typo was due to a phone keyboard, or maybe another common reason humans give for their typos. Though it's super unlikely that it will give the true reason: that it's been trained on text that exhibited this property.
That's a fundamental difference between an LLM doing an exceedingly competent job at pattern matching human behavior and real human behavior (unless maybe you're a human with schizophrenia).
That doesn't mean current LLMs aren't useful, but it does mean there is a very significant gap between them and the idea of an AGI. As a NLP researcher, I can confidently say we currently don't know how to imbue agency (as in embodied causal reasoning as I described above) into LLMs. There are definitely differences of opinions on how difficult that step is and if we are close, but it is a major limitation of current LLMs that can't be ignored.