I'm not insinuating that all artist should to use Campbell's Monomyth in their work, there are millions of mythological stories across thousands of cultures in history, and any little bit of them can describe something that moves in us. They are waiting for you to use them in order to build something new.
The Greek myth of Leda and the Swan does not follow Campbell's rules. To me, it's one of those myths that is open to interpretation. It's a shady cove, an eddy in the river of story, a place where you can spend some time. And frankly, it's so weird that it tickles your imagination and asks to be appropriated.
• The Myth: Leda is raped by Zeus in the form of a swan, on the same night she has also become pregnant by her husband Tyndareus. She lays two eggs which hatch 4 children. The order of the births, who was in each egg and sometimes, who is the father of each child is disputed. But they are: Castor and Pollux (The Gemini) Helen (who's ship-launching beauty will ignite the Trojan War) and Clytemnestra (who will later take up a symbol of Greece the Labrys, and behead her husband Agamemnon for sacrificing their daughter to the Gods in order to gain a good wind.)
• In art: A look at this Pinterest collection will point out that MANY artists through the ages have tackled this myth, from Michelangelo and Klimt to Cy Twombly. Salvador Dali even designed a Leda Chair that he put into a painting, which some mad wizards actually made.
Historically, it gained the most popularity as a subject in the 16th century, a time when it was considered imprudent to depict two humans in the act of making love. Zeus' form was a convenient workaround for artists interested in showing the sexual appetite of man. Through the years the scene has been portrayed as literal and as allegorical, sometimes even provincial; newly-hatched little babies at Leda's feet crawling around with eggshells as hats, with complete disregard for the fact that soon these chubby little egg-born rape babies will become harbingers of battle and leave whole cities burning in their beautiful wake.
And some artists get at the surreality of the act itself, the physical weirdness of it, and the doom that came from Zeus' appetite.
W.B. Yeats wrote a sonnet about it in 1924:
A sudden blow: the great wings beating still
Above the staggering girl, her thighs caressed
By the dark webs, her nape caught in his bill,
He holds her helpless breast upon his breast.
How can those terrified vague fingers push
The feathered glory from her loosening thighs?
And how can body, laid in that white rush,
But feel the strange heart beating where it lies?
A shudder in the loins engenders there
The broken wall, the burning roof and tower
And Agamemnon dead.
Being so caught up,
So mastered by the brute blood of the air,
Did she put on his knowledge with his power
Before the indifferent beak could let her drop?
Yeats, right?