The Legend of Zelda: Ocarina of Time uses music as a game mechanic, the design of which requires Link to be a musical genius. The songs that Link learns to play on his ocarina serve multiple purposes. From warping to adjusting the water levels in the Water Temple, Ocarina of Time would be more difficult without Link's innate musical talent.
As the titular object, the Ocarina serves as a key item in Ocarina of Time. Under the guidance of Navi, Link travels between two timelines seven years apart to awaken Sages who will help him defeat Ganondorf and end his destructive reign over Hyrule. Link receives help from several characters throughout his journey, but Sheik in Ocarina of Time possibly provides the most aid by teaching Link songs.
In Ocarina of Time, Link only needs to hear a song once before he can play it perfectly. His ability to play by ear after hearing a song isn't the extent of Link's musical genius, though. When Sheik teaches Link a new song, it's done with a harp, and Link can still repeat it without issue on the Ocarina. Considering that Link most likely never received formal music training, this is an impressive feat. The ease with which Link masters new tunes is necessary from a game mechanics standpoint, but in-universe he would likely be a musical prodigy if he weren't busy saving Hyrule.
Link Is A Musical Genius In Multiple Zelda Games
Ocarina of Time isn't the only Zelda game in which Link displays a talent for music. More than one character from Ocarina shows up in Majora's Mask, and the Ocarina is a recurring item in both games that has critical uses for completing them. Depending on the mask that Link wears, the ocarina changes to a different instrument, and he still as no difficulties playing the songs. In A Link to the Past, he plays a flute for Flute Boy without issue after finding it. Link's Awakening relies on music to wake the Wind Fish, and Link needs to use eight instruments for this task, but he accomplishes it easily.
It's probably tiring for Link to always be the hero in Zelda games. With the task of saving Hyrule placed on his shoulders, Link has to showcase a variety of skills to overcome the obstacles he faces. From solving puzzles to reach the end of dungeons to fighting the creatures that stand in his way, Link needs an array of abilities to fulfill his destiny as the hero of Hyrule. However, if being the hero didn't work out for Link in Ocarina of Time, he could have had a future as a musician.