“Based on most Upper Palaeolithic cave incursions, we could assume that they represent some kind of symbolic or ritual behavior, but could they rather have served for an unknown domestic use or simply as a refuge?”
Or perhaps, just perhaps they found it amusing, much like modern-day adults are building sandcastles the size of a bull, or are placing rocks upon rocks, or stack wood, or something. Who said that everything a human does absolutely has to serve some important and complicated purpose?
Apparently we raised a generation of accountant-researchers. They maight be skilled in their relevant fields, but they no longer have the creativity and imagination required to understand people, life and the world that surrounds them.
Somewhere out there, Feynman is rolling in his grave.