What is the oldest example of the Joseph Campbell's monomyth (AKA: Hero's Journey) story structure ?
I know about Homer's Odyssey (circa VII BC). Are there any older examples ?
While I'm not an expert on literary analysis, I highly suspect The Epic of Gilgamesh is going to be the one we have the oldest evidence of.
Its a very wide ranging story, but the hero Gilgamesh does go on a journey, and return to his home in Uruk at the end. At the beginning, he's a bit of a tyrant, while at the end he's been humbled by loss, and expresses appreciation for the works of Uruk.
Some of the tablets we have of it date back to the 22nd Century BC. At that time, the only other places we know for sure even had writing yet were Egypt, Elam, and the Indus Valley.