>Probable given what?

The training data..

>predicting what intelligence would do

No, it just predict what the next word would be if an intelligent entity translated its thoughts to words. Because it is trained on the text that are written by intelligent entities.

If it was trained on text written by someone who loves to rhyme, you would be getting all rhyming responses.

It imitates the behavior -- in text -- of what ever entity that generated the training data. Here the training data was made by intelligent humans, so we get an imitation of the same.

It is a clever party trick that works often enough.