The plot follows the life of our protagonist 1900--yes that's his real name--who is found in a lemon crate by a black stoker named Thanks Danny on a steamship in the first class section of the boat. He's raised by Thanks Danny until Danny dies, and then is unofficially adopted by the rest of the stokers and the indulgent (if ever rule conscious) steamship captain. At a young age he first sits down at a piano and can play brilliantly and thus earns his keep by joining the on board band. Jump ahead to when 1900 is 27 and he meets the new trumpet player Max Toomey, who instantly becomes his best friend in what is IMO one of the most inspired and whimsical sequences of the film:
The "Magic Waltz" Scene
I mentioned the film in my post Whatever Happened to Romance? as the perfect example of what I call "Ironic Romance" which is a type of Romance where the heroes are more human and less divine, and the tropes of Romance are nearly all reflected in an ironic manner that doesn't go to the point of Satire in parodying them, but instead gives an "unusual twist" to the expected trope.
I should mention that since this exists in the mythos of Romance pondering questions like "where does he get his clothes if he's never left the ship?" are pointless to be asking as Romance is more concerned with life from the neck up--not the neck down, and you'll only be creating for you a more frustrating viewing. Romance and complete realism can never really coincide--accept that and move forward. Having said that though, I will say that Ironic Romances such as this are as close as the genre of Romance will come to existing in our own secular and scientific world.
Here are our "main" characters and the archetypal roles of Romance they fulfil:
1900 - Hero
Captain - the Helpless Old King
Max Tooney (our narrator) - the Sidekick
Jelly Roll Morton - the Dragon
The Girl - the Princess
This is a good example of stage six of the mythos: "The Happy Society ceases to exist beyond contemplation. These are tales often told in quotation marks by one individual to a small group; there is a coziness to this type of tale as it is free from confrontation and has a relaxed and entertaining tone." -- Northrop Frye
Here the "pastoral world" of the Progressive Era (1900 - 1918) & Jazz Age (1918 - 1929) transatlantic steamer with all its Art Nouveau style of interior design (which is reflective IMO of the "pastoral" in the ironic sense--instead of being an "Arcadian forest glade" we're given the "floating city") has ceased to exist thanks to WWII turning the ship into a hospital ship and then being decommissioned to be sunk at the end of the war. The film is told in a series of flashbacks which are the "quotation marks" Frye speaks of, by Max Tooney to a British pawnshop owner as he contemplates selling his trumpet.
While 1900 is a hero, he's a hero who's biggest challenge is whether or not he should go out and live his life. Here the sense of the "heroic" is conflated with living a normal life and we're asked to ponder if a hero can actually live a normal life, marry, and have children--while still remaining a hero. He actually finds the "pastoral" world of the ship comforting and complains that the world off the ship is "too big" for him. Since this is stage six, this is not as surprising as if it were "stage one", because usually the sixth stage of a mythos is the "ironic variation" of a mythos (watch The Princess Bride)--and this is no exception. And so we have a "hero" who's afraid to leave the world of the ship he's always known--instead of being the typical "hero" who wishes to go out and "see the world". If this were purely Satire, we'd find the situation hilarious, and it would be meant to be hilarious, and we wouldn't be allowed to empathize with his character. However since we are in the last stage of Romance, it is merely verging on the edge of Tragic (the next mythos after Romance as per Frye), and is only "funny" in a sad way upon reflection, which I guess is fitting for a ironic "hero". However at the same time if 1900 were to leave and "go live a normal life" he'd lose his connection with the divine that he has while being on board the ship and at sea. He is a child of the sea foam--and the only appropriate ending for his story is to be reunited with the sea from which he came, if he is to remain a hero. If he follows the advice of others and goes and "lives a normal life" as "the girl" invites him to do or "goes to see the world" as Max Tooney asks of him, 1900 would no longer be what he is--and that would be a true Tragedy. So while giving slight overtones to the Tragic, The Legend of 1900 still stays firmly in the realm of Romance, ironic Romance to be sure, but still completely a Romance.
As befits a slightly ironic "stage six" Romance, our "hero" doesn't go out in search of a quest, the quest finds our hero and chases him. With his "dragon to slay" being a duel with Jelly Roll Morton--the creator of Jazz--who seeks 1900 out, not the other way around. And ironically enough, 1900 goes out of his way not to best Jelly Roll Morton, which upsets Jelly who sees 1900's unwillingness to actually challenge him as a dismissive mood, and it's only when Jelly verbally insults him that 1900 actually competes. Which I guess is to be expected from such a "hero"--they only perform when pushed into it.
Romance is always on some level about being in touch with the divine--as the traditional Hero always is, whether they speak to the divine such as Oddyseus (from The Odyssey), whether they visit the homes of the divine such as Dushyanta (from Shakuntala), or whether it's a more spiritual connection such as 1900 has. In this film the divine is represented by the Ocean, and 1900 feels that the Ocean "talks" to him: "you can hear its voice, it's like a big scream telling you that life is immense, and once you finally hear it then you know what you have to do to go on living." One thing that is quite ironic about this however is the fact that the ocean in the mythos of Romance typically is the force of "Chaos" and not typically part of the divine realm, so to have the typical force of "Chaos" become the force of the "Divine" in this film is very ironic for a Romance, but somehow the film manages to make it work without delving into the realm of satire.
Last but not least, we need to speak of the 1940s, where the ship has become a wasteland, a relic of the old society (the Great Power Saeculum) that is being destroyed as a new society (the Millennial Saeculum) is being born. What is more emblematic of the extinction of the "happy society" than the destruction of the ship. The film is mostly set in the 1920s (and being told from the post-war 1940s POV of Max) and turns them into a lost "golden age" (as all Romances are set in "golden ages of yore" with a nostalgic lens).
If you have a free rainy afternoon, I'd suggest popping a bowl of popcorn and viewing this neglected little gem of a film for you to watch.
Here's the trailer to whet your appetite.