The Hero's Journey is a framework that scholar Joseph Campbell came up with that many myths and stories follow. Many storytellers and story-readers find it a useful way to look at tale. (That's actually putting it lightly. Some people are straight-up obsessed.) Chris Vogler adapted Campbell's 17 stages of a hero's journey, which many screenwriters use while making movies. Vogler condensed Campbell's 17 stages down to 12, which is what we're using. Check out a general explanation of the 12 stages.
The story of "The Great Deluge" doesn't fit perfectly into the Hero's Journey structure, but we're giving it a shot. As the gross old saying goes, there's more than one way to skin a cat.
Deucalion and his wife, Pyrrha, chill out in Thessaly, having a good old time. Things are pretty awesome.
Call To Adventure
Deucalion's dad, Prometheus, warns his son that Zeus is sending a flood to destroy all of humanity. Prometheus advises his son to build a floating chest to save him and Pyrrha.
Refusal Of The Call
There's no refusal here. Deucalion gets right to work.
Meeting The Mentor
Prometheus is totally the mentor. He tells his son what to do, and Deucalion wisely follows his dad's advice.
Crossing The Threshold
When the waters start to rise, Deucalion and Pyrrha are swept into a world of adventure.
Tests, Allies, Enemies
Well, Prometheus has definitely proven himself to be an ally. While Zeus doesn't target Deucalion and Pyrrha specifically, he's certainly not doing them any favors.
Approach To The Inmost Cave
It seems like this step already happened while Deucalion and Pyrrha were waiting for the waters to rise.
A gigantic flood drowns everybody on earth, and you're stuck in a little boat—yeah, we'd call that an ordeal.
Deucalion and Pyrrha make it through the flood and land on the peak of Mt. Parnassus where they're rewarded with... well... being alive.
The Road Back
The happy couple makes it back to dry land, so that kind of counts, we guess.
Usually this is the part where the hero goes through a final terrible ordeal and barely comes out alive. Although the worst ordeal is over for Deucalion and Pyrrha, there is a major resurrection here when the couple throws rocks over their shoulders and regenerate the entire human race.
Return With The Elixir
Deucalion and Pyrrha return to their life together and have lots or babies, having been made stronger by the whole ordeal.