Could also just be someone with mental illness ostracized from society at the time.

Without being an expert that still seems very unlikely to me.

The epic was written around 2000 BCE which was well over >> 10k years after agriculture and more than 4 times that much after neanderthals died out.

It's possible but much more likely that they refer to something more contemporary. There are always "wild men" around no matter who you ask.