Sexual politics and "The Little Mermaid" (1989)
Ignore the original story; Hans Christian Andersen tapped into something, but he was chewing raw leaf compared to Disney's crackpipe to the psyche. We're focused on the 1989 film version that kicked off the Disney renaissance, wherein the pre-internet-saturation generation was permanently mkultra'd into a new consensus mythos via VHS. What did Hollywood manage to convey with this one?
The laziest read of this, and an effective consensus in surface interpretations, is "yay, women". Stunning and brave Ariel is a woman now! Yay! That means she has agency and can go on big adventures and nothing works out badly for her in the end, because pluck and believing in yourself. It is too boring to relate at length. (It has also recently been repurposed by the trans disneyphiles, who relate not to her transformation into a woman, but into a different sort of beast entirely who manages to "pass" in an alien world. The fact that she happens to be hitting legal adulthood is incidental, she could just as well have decided at the age of four that she was a biped and required medical intervention rather than a magical bargain).
But this isn't just any mermaid, she's a princess, daughter of a king. Every story of a royal house ipso facto has political implications, and when rule is by blood, "marriage" (which is to say, sex - the propagation of the blood) is a political act. In this interpretation, Ariel is not so much the "main character" as a swimming MacGuffin - she moves the story so that other actors (specifically her father, King Triton, and the antagonist, the Sea Witch Ursula) can exercise agency and advance the plot.
So how does this MacGuffin come into being, and what is it a stand-in for? A treasure introduced in Act I is obviously gesturing at the universal desire for wealth, a super-weapon the desire for power - and a woman, the desire for sex or sexual security. But in this case, the woman is not the object of desire, but rather the subject. Bluntly, Ariel is a stand-in for female sexuality unchained, a chaotic force that merely by chance does not end in disaster, and is allowed to escalate as far as it does primarily by the weakness of men in restraining it.
The fetishization of the Other is a time-honored tradition, and the linkage of Ariel's escalation in efforts to contact the Other with her dawning womanhood makes it clear that she wishes to be conquered by the alien realm of the surface. Her continued intrusion on the surface, in other words, does not indicate a scientist's desire to understand, or a warlord's desire to establish sovereignty, but rather a woman's desire to sexually consume. It is noteworthy that in order to experience the surface, she does not seek some sort of reverse-submersible, but eventually legs, and what lies between them.
So she falls in love with the first noteworthy surface dweller she sees - so handsome! King Triton senses disaster, and tries to forbid her from pursuing catastrophe, but he is weak - he concedes guardianship of his daughter to his ineffectual court composer Sebastian but allows her to do as she pleases (I guess it's trickier to keep her in the traditional tower at neutral buoyancy). Not meaningfully constrained, Ariel compounds the problem by making a Faustian deal with Ursula, the Sea Witch, for a temporary transformation into a human at the cost of her voice. Should she get "true love's kiss" within three days, she will stay on the surface, or else be consigned to servitude.
The loss of her voice is always a "what did they mean by this" point of fixation in analysis of the written work. In the Disney rendition, with the animator's ability to convey body language with more fidelity than the page, it is much clearer - there will be no higher-order appeal here, but a raw physical seduction. "Without my voice, how can I..." she stutters, before the Sea Witch helpfully informs her of what she knows instinctively - talking is superfluous to the whole endeavor. Take a shot every time Ariel approaches, purses lips, and leans up for an embrace, and be dead by morning.
But nonetheless, with some minor interference, at the last moment Ariel loses the bargain, and her soul. Her MacGuffin status is reinforced - it turns out the Sea Witch's bargain was merely intended to get leverage over King Triton, who can get his daughter back at the cost of his kingdom.
Triton's role in this is under studied. He has six other daughters - in other words, he is in no danger of running out. Kingship 101 is that once you give up your crown, you are as good as dead, but apparently no ship ever sank carrying a copy of Machiavelli. Yet again he fails the test and concedes.
It is here the story should properly end. At any point, a tiny bit of pashtunwali could have solved the problem, but it's too late - the ocean belongs to satan now. Instead essentially by chance, the prince is able to pilot a shipwreck to stab the Sea Witch in the heart (we don't even get the decency of a setup where the Prince is shown to be an unusually good pilot). Ariel and the prince kiss, Triton concedes yet again to his daughter's desires and transforms her into a human to get married, and everything is fine (until the dynastic struggles I'll just blithely assume happen in Little Mermaid 2, where Triton's lack of male heir causes a ocean / surface war in furtherance of Ariel's son's claim. Or maybe they skip ahead and it's just King Lear in an aquarium. Who can say?)
Triton evidently didn't get his throne by guile, because his takeaway from this incident is to take his composer's advice that "children got to be free to live their own lives". No! That's what just happened! Your entire family was almost murdered! You were enchanted into some kind of a sea worm as a result! Mirror Universe Triton would take this opportunity to send a tsunami to the Prince's kingdom, arrange for Sebastian to be eaten by a seal, and never speak of the matter again.
Instead, we live happily ever after.