I finally finished skyward sword so now I can actually put out my basic reading of the Zelda Religion Thing without being accused of skimming.
Early Canon History As Said To Skyward Link:
Three Golden Goddesses/The Old Gods/Trio create the world. They create Hylia, to essentially be the guardian deity of the world, and the triforce, which represents the Trio's power of creation. Then they leave, ala clockmaker theory (the theory that a god created the world and then let it go ticking on its own, like a clockmaker, because once they've made the clock it's supposed to continue to function on its own)
The Triforce is the power to shape the world through desires/wishes, but it can only be used by mortals: immortals like gods can't use it. Hylia is guarding it and can grant access to it (she decides the best way to decide who gets it is through fucking puzzle labyrinths) but can't use its power herself.
Demise shows up to consume the world. Things get very confusing but at the end of the fight, Hylia has won a phyrric victory, Demise is sealed but not destroyed, and Hylia become mortal voluntarily thus entering the reincarnation cycle. It's implied in wikis that Hylia becoming mortal releases the Triforce to be able to use it? but that is the part that mainly confuses me. Regardless, Hylia stalls for time until later reincarnation of her finds someone (Link) who is capable of wielding the Triforce as her Proxy.
(Unnecessary note on reincarnation: The person who can wield the Triforce is assumed to be the same soul reincarnated over and over, but this isn't strictly provable, and aside from considering them a precious person, all Zeldas and Links are treated as separate people, just with 'the bloodline of the goddess' running through them, but like... You go back far enough and it's all the same bloodline. If all humans in Skyloft eventually became Hylians, then all Hylians are descendants of the goddess' people. If we take it as a literal bloodline, this also means that a lot of Gerudo probably are also in the bloodline, since they usually intermarry with Hylians. And if it's a metaphorical bloodline, then we literally don't have to worry about it lmao.)
So with the setup the games have given us, this is how I think the religous setup of Zelda works:
Hyrule's World was set up in a Creation/Destruction cycle. This is pretty natural, and an instinctive way to set up a world. Hylia is a Cultivator Goddess (mother goddess, one who raises but doesn't dominate), and Demise is literally called Demise: he is either a manifestation of Entropy on this plane, or was created by the Golden Goddesses also as a yin-to-yang situation, where Demise would destroy things that Hylia created, leaving more room for more creation later on, like how a volcano erupts burns everything down, but new land grows from that eruption.
The issue comes when the cycle became imbalanced. One thing that keeps coming up with Ganon is that he equates rule and destroy pretty equally. He will rule Hyrule! And it will be destroyed. But also he will get rid of the barren ocean! He will create a new Hyrule... which he will rule over with a harsh hand uwu.
It sounds to me like Demise wanted to at some point take Hylia's role as the creator/guardian Diety, but his power is literally destruction. So the way he understands raising something is like... to the ground. It is a fundimental Nature Thing that influences his understanding of the world. If he destroys the world, he is making it anew maybe, or maybe the monsters are his equivalent of Hylians, or etc. Regardless, his plan is basically "I'm in charge now and it will be Better", and there's nothing beyond that--he's good at his job and he's sure he'll be excellent at this other job as well.
At some point after Skyward Sword and being defeated by a Hylian with the Triforce, he changes strategies. I'm not certain if the plan was to get the Triforce of Power because it is the most powerful of the three, or if he meant to possess all three pieces and only managed to grab one, but his attention turned to claiming the Triforce instead.
The Triforce, which holds the ability to shape the world they live in (the power of a creator god, available to the beings in the world it shapes) is only attainable by a mortal, so Demise does as Hylia did, and becomes mortal.
It is... difficult to figure out how to talk about Ganondorf without discussing racism inherent in the design of the Gerudo. But at some point Demise has a connection to Ganondorf of the Gerudo, either that being the mortal form he's been reincarnated into, or "a manifestation of Demise's hatred." It could be chance that Demise became a Gerudo, or like... deeply unfortuante implications that I don't want to deal with for a Watsonian the-religion-is-true type speculation?? Doylian answer: the real world had racist influences. Watsonian answer: Gerudo have the goddess bloodline too, making them capable of wielding the Triforce, and it's just deeply unfortunate that the dieties in this world have strong opinions on their gender.
So as Demise becomes Ganondorf, he starts doing the thing Hylia did upon becoming mortal: gains the fun mortal emotions and experiences, and becoming less godly. The Power Triforce allows Ganondorf to live a very long time, so sometimes he's the same person between Zelda/Link incarnations, and that also gives him a long time to build up mortal experiences.
He is no longer a being completely of hate, but he has yet to obtain the power of 'creation' the way Hylia has it, because of his inherent roots as a being of destruction and entropy. Even when he intends to make something, his method for doing so is through destruction. In Wind Waker, he's furious that Hyrule's been flooded, but the ocean is a dead and barren place, and he wants to fix it: he wants to positively change the world... and he does it by ripping the seas apart trying to find the Triforce.
Conversely, Hylia is a being of creation/preservation, which is why she can't directly fight effectively. She can make prisons to seal Demise away, but that's still creating a prison. She can make light arrows, but needs someone else to fire them. She can make a master sword, but needs someone to weild it for her. That's why she sends out heroes as proxies in the fights. She isn't an omnipotent type deity. She gave up a lot of her power to get the triforce, and she can't walk it back. I see a lot of fic with Links frustrated that Hylia has 'put them in this position' or 'relies on young kids', which like, I get? But you have to think smaller gods. She has power on her own, but not the power of outright destruction, which is what she needs if she were going to destroy Demise forever. If she did manage to destroy demise, presumably she would then take up the role as both creator and destroyer? But since she's locked in mortal form, maybe the world is already functionally goddessless, which is why the only working relics are things from the ancinet past, when she was immortal, and killing Demise now would mostly just mean less Ganondorf-based events in the world, but otherwise not change much.
Hyrule is locked in a very degraded creation/destruction cycle, where the creation goddess is finding ways to destroy, and the destruction diety is trying to create. Both of them are mortal, leading to huge stretches of time where one or both are dead or sealed away, and when that happens, the Triforce is sealed away with them: it can only be used when all three parts are combined. So Hyrule, a place with absolutely 100% proven godly magic, is fully unable to use it to change their environment for long stretches of time.
This is. A very busted clock.
