Hear me out now, The Legend of Zelda is a sucess because it takes risks. Like what other series has a dancing game (Cadence of Hyrule), a game where the entire plot is literally dress up (Triforce Heros), and a game where there isn't a single dungeon-like structure that has been such a staple to the franchise in sight (Hyrule Warriors), Sure, not all of these games I just listed are canon, but that is exactly why The Legend of Zelda has been so sucessful.
It draws people from completely different areas of gaming and brings an experience that so many unique people can enjoy together. Theses a game for everyone: Linear players (A Link to the Past), open world (Breath of the Wild), a game with tons of in game lore to dissect (Skyward Sword), and a game with very little lore in game (Legend of Zelda), There's a game for everyone's preferences from 2D (Legend of Zelda) to 3D ocarina of Time) and even a few games with both, most notably A Link Between Worlds.
Heck, Nintendo was so willing to take risks that they made the 2nd game in the entire series an ARPG ( Zelda II: Adventure of Link)! In the 3rd ever game they didn't even put the main title character (Zelda) in the game (Link's Awakening). Now, when Nintendo was forced to play their hand and supply the fans with a long awaited timeline they didn't cower in fear from backlash for a split timeline that even killed on of their beloved heros (Ocarina of Time/ Downfall Timeline).
And when the public was expecting a Twilight princess they gave us a toon link (Wind Waker). Sure, people hated it at the time, but now The Wind Waker has turned into a game that continues to make many peoples lists of favorite games to this day. When everyone wanted open world they weren't afraid to give the characters audible voices despite how much backlash they knew they wold get for the voice acting (Breath of the Wild). Lastly, they didn't care what the fans would say when they rewrote the founding of Hyrule (Tears of the Kingdom).
What other series allows the main character to drive trains (Spirt Tracks), save dream Worlds (Phantom Hourglass, Link's Awakening, ((and Majora's Mask if you're of that belief)), turn back time (Ocarina of Time, Majora's Mask), transform into a beast (Twilight Princess), play as the "damsel in distress" (Echos of Wisdom, Spirt Tracks), split into four (Four Swords, Four Swords Adventure), link two games together and fight Ganon (Oracle of Ages, Oracle of Seasons), and so much more?
The Legend of Zelda is a huge success because thy aren't afraid to take the unpopular decisions and make risky choices. These risks have paid off tenfold.
