Dragons found beauty in the internal structure of mana. The way they wove their concepts, the way those weaves came together to form a spectacular picture, and other similar aspects were what dragons saw as pure beauty that could not be imitated.
However, that was only possible because dragons inherently had such a good perception ability. Humans didn't gain a similar level of ability until they'd reached a high level, so they could not share the same interests.
For humans who had yet to become Divinities, the beauty of mana came in its form. People were able to manifest things that they could only see in their imaginations, using mana to bring their dreams to reality so they could achieve their dreams in reality.
It was a bit more materialistic, sure, but wasn't that the nature of humanity? Why did it matter if it was materialistic in the eyes of others if it was beautiful in the eyes of those who mattered?