AI designs will start to look more (biologicaly) evolved, less intentionally designed. Museums, especially older ones are full of jars with pickled specimens, bags of bones and tubes and strings which somehow seemed to fulfil their purpose. Humans will study the objects to find out what makes them work.

You can imagine a scenario where the pervasive use of AI has dumbed down humanity so much that they can only stare at the intricate designs while marveling at the omniscient creator which must have been behind it all.