Hylia's Chosen Hero

Hylia's Chosen Hero, also known as the Knight of Hylia, is a hero chosen by the Goddess Hylia in an era shorly after the creation of the world by the Golden Goddesses, thousands of years prior to the events of Skyward Sword. Although only briefly mentioned in the game, Hylia's Chosen Hero plays a significant role in the Skyward Sword manga, where he is depicted as the earliest incarnation of Link. This has not been confirmed canonically. In the manga, the Goddess's Hero is clothed in Link's signature green garb, as well as a red cape and golden armor placed on his shoulders. He is also depicted to be in his adult age rather than being a late teen.

Backstory
Little is known about Hylia's Chosen Hero's story except that he lived on the Surface during the Era of the Goddess Hylia. According to the legends, Hylia made him her chosen hero and gave her blessed Sailcloth to him.

The Hero's Successor
Eventually, the successor of the Chosen Hero was prophisied by his chooser, who was destined to fulfill his destiny as the goddess's second hero. Hylia created Fi, the spirit that resides in the Goddess Sword, and gave her the purpose of assisting Hylia's Chosen Hero's successor throughout his journey.

Skyward Sword Manga
In the Skyward Sword manga by Akira Himekawa, Hylia's Chosen Hero is an incarnation of Link. He lives in a city in the world below the clouds known as the Land of Hylia.

The Hero's Return
Link becomes a Knight of Hylia, respected by the Hylian citizens and regarded as a hero. However, the hero is imprisoned for four years after his sword, Orville, is broken, and he is deceived by Lord Dagianis, who is killed four years later by Demise. After his death, the people free the Knight of Hylia from his prison. They say that he is the only one capable of saving the land from Demise's army of monsters, then give him his repaired sword and his clothes. The Knight of Hylia, Link, appears atop the castle, facing a crowd cheereing for him. Gazing at the sky, he says to himself that he will fight for the Goddess Hylia forever as long as she needs him.

The Goddess and her Hero
Ready to fight with his allies against Demise and his army, the Goddess Hylia suddenly appears in person, riding on an old Loftwing. The articulate Loftwing expresses his low opinion of the Hylians, saying that they are useless and didn't know the differences of deities and monsters. He could not believe that the hero who would ride him and face Demise could be among the people of the Surface. Link reveals himself as the Knight of Hylia and the hero whom they sought. He claims that, although humans may seem small in the eyes of the gods, there are those among them who possess great courage. Hylia acknowledges her knight's unmatched valiance and honor and proclaims him again her chosen hero. She then allows him to wield her legendary weapon brought by the gods, the Master Sword. However, the hero claims that he could not touch a holy sword, thinking that he is impure because he was imprisoned for years. Despite this, Hylia says that the Master Sword will decide whether he is impure or not, and asks him for his choice; to seek revenge on the surface's people who imprisoned him or to save the world from its terrible fate. Hylia's Chosen Hero decides that he will always stand with his friends and accepts the Master Sword from the goddess.

The Battle Against Demise
Hylia's Chosen Hero and the Goddess' army had been fighting Demise and his army of monsters for a week. The hero is wounded by the Demon King, and as he is about to pass on, the Goddess's Loftwing allows him to ride on his back and fight together. The hero asks for the Loftwing's guidance to show his people to the skies, to which the Loftwing agrees to as long as the hero continues to fly with him. At that moment, the three legendary dragons, Faron, Eldin, and Lanayru, appear, offering their blessing to Hylia's Chosen Hero's Master Sword. It is then revealed that the legacy of the gods dwells within the Master Sword. The hero gives the holy blade to the Goddess, so she can send the Hylian people and their kingdom to the skies with a single sweep of the Master Sword. The Goddess sends it back to the hero and makes the Master Sword a pillar between heaven and earth. Hylia's Chosen Hero, who is gravelly injured, stays behind and watches the land floating through the skies before passing away. After the Goddess Hylia seals Demise, she returns to see her hero, who has already passed away. Crying, she states that she will be reborn with her hero and live with him as a normal person, casting off her title and ensuring that his heroic spirit will live on forever.

The Chosen Hero's Rebirth
Thousands of years later after the Hylia's Chosen Hero and the Goddess save the world, the hero's reincarnation, Link, goes outside and encounters the Crimson Loftwing, who is actually the reincarnation of the Goddess's Loftwing. The bird's eyes tells a message to Goddess's hero's spirit, which resides within his successor. Young Link then seems to understand the Loftwing who chose him to be his rider.

Incarnation of Link
Hylia's Chosen Hero may himself be an incarnation of Link, as portrayed in the manga. In an interview, Eiji Aonuma stated the possibility of future games taking place before Skyward Sword in the Zelda Timeline. If this were to occur, Hylia's Chosen Hero would be a likely candidate for the next Link in the series (or the first, chronologically). This Link would be first to possess the Spirit of the Hero which would be passed down onto his descendants, especially his successor from Skyward Sword.

The Chosen Hero's descendant
Hylia's Chosen Hero is briefly mentioned during the events of Skyward Sword and it is hinted that Link is the descendant of the hero. Link in Skyward Sword therefore inherits the hero's spirit and powers, making him the only one to defeat Demise.

The Chosen Hero Reborn
It was hinted many times that Link is the living embodiment of Hylia's Chosen Hero. The spirit of the hero that he possessed was then transfered into his successor, as he is the chosen hero before Link thousands of years prior the events of Skyward Sword. As Link possesses the spirit of the hero, it makes him the hero's reincarnation, so he could continue fight for Hylia and her incarnations endlessly. Link is the person who possesses the hero's unbreakable spirit, who the Goddess Hylia needs to defeat Demise. However, just having Hylia's Chosen Hero's spirit wasn't enough; Link needed to awaken the spirit of the hero within himself. It was known that Link also played the role of his ancestor at the Wing Ceremony with Zelda playing the role of the goddess. However, in the manga, it was confirmed that Hylia's Chosen Hero and the Goddess Hylia are reborn together thousands of years later as Link and Zelda, as Hylia wanted to live as a normal human being with her hero.

Goddess Sword/Master Sword
It is probable that Hylia's Chosen Hero was also wielding the Goddess Sword during the Era of the Goddess Hylia, until one day, the hero managed to turn it into the Master Sword, as seen in the manga.

Trivia

 * In Skyward Sword, Hylia was said to be severally injured during the battle against Demise. She was also the one who created Skyloft. However, in the manga, her chosen hero was the one who was critically injured by Demise and brought the Kingdom of Hylia into the heavens with the Master Sword.