100 years ago, Calamity Ganon revived and wreaked havoc on Hyrule despite the populace's preparations, by taking control of the ancient technology they had unearthed in order to try and fight back - namely the Divine Beasts and Guardians, the latter of which you might've seen look like giant spider-y robots. Link fell to the corrupted Guardians trying to protect Zelda, who had yet to awaken her sealing power. Her mother had died when young before they could begin her spiritual training, and without guidance she struggled to evoke the Goddess blood within her (see Skyward Sword for more info on how Zelda herself is a reincarnation of the Goddess Hylia), suffering from severe self-esteem issues as a result. Her father would only put more pressure on her to devote herself to prayer, out of desperation due to the looming prophecy foretelling Ganon's return and not knowing any better recourse. He harshly forbade her from studying the ancient relics, which she found comfort in as she possessed a keen knack and passion for science. Beyond her personal interest, Zelda believed it the best way for her to be of use if she could not harness her own latent ability, but her father saw as only a distraction from her "duty" as princess.
While Zelda was finally able to access her sealing power when Link's life was threatened, it was too late - he had suffered fatal wounds, and needed to be placed in the "Shrine of Resurrection" in order to recover. However, it would take 100 years for his body to fully heal, and he would lose his memories in the process. Zelda instructed her followers to take him there, while she went to Hyrule Castle alone and placed herself and Calamity Ganon into stasis as well, holding on with all her might while waiting for the hero to arrive. The kingdom enters an era of tenuous "post-apocalyptic peace" as 100 years slowly pass, Link eventually opens his eyes, and the game takes place. By the end, he reaches Zelda just as her strength is starting to fade (according to game timeline logic obviously) and the Calamity is once again released. They manage to defeat Ganon together, and Hyrule is saved - sorta, considering all their friends and family are still dead, among the countless other civilians killed in the initial attack. The two are still their same selves from 100 years ago, just among the few only living survivors from that time (and in Link's case, lacking memories depending on how many the player chose to unlock).
In Age of Calamity, it's revealed that as a child, Zelda either built or repaired her own miniature "Guardian" as a companion - named "Terrako" - which also became her emotional support after her mother's death. Her father took it away though, thinking it a "toy" that she should no longer be playing with and instead focus on her training. When Zelda's powers were triggered, they also had a remote side effect of reactivating Terrako, who had been dormant inside a box in her room at the castle. Heeding her wish to "protect everyone", it somehow opened a temporal rift and traveled back to shortly before the Calamity struck. (Whether Zelda's power infused it with time-traveling capabilities or it possessed them all along is unclear.) Suffice to say, this created another new split timeline where they do manage to succeed in stopping the Calamity the first time around.
From here, I'm just gonna copy my thoughts from the description of the video:
While the story can be considered contentious for many reasons, after thinking on it, I've come to the conclusion that this *was* a well deserved ending - or rather potential outcome. It is the culmination of all of Zelda's personal efforts and hard work that didn't get to fully bear fruit in the main timeline, if only she had been permitted to pursue her passion for research and relics. Here, everyone's survival and happiness - including her father's - is a direct result of her ingenuity in crafting Terrako as a child. BotW had hinted that Zelda's knowledge of ancient technology might have proven key to total victory 100 years ago had she been allowed to nurture it (along with her sealing power), and AoC now provides canon confirmation that it is the case. ...And I can gladly accept that.
TL;DR Techie nerd Zelda is valid and AoC shows how following one's heart and dreams (preferably with parental love/support as extra encouragement) can make all the difference thanks for coming to my TED Talk