It's an old joke. It was mocking parents of millennials who called every game system "a Gameboy" or "a Nintendo" and called protagonists of the game by the title, like Halo for Master Chief or Zelda for Link.

The joke is mostly played up. Most of the time adults just didn't care or leaned into the cringe for fun, but that is my experience around it. Gaming has become so prolific since then that the joke has been beaten into the ground and resurrected elsewhere (see streamers calling their characters John Ring for Elden Ring or John Halo, as examples).

It's just a silly joke about people not knowing about games. You can see other, similar, humor in people calling Tim Cook 'Tim Apple' for example, but that obviously has different origins, it's just kind of a similar idea.

It was fairly common when the first game was popular. There wasn't much dialogue, and none of it mentioned Link's name. I'm honestly not sure it even mentioned Zelda's name.

I do remember, though, that if you named your save file Zelda you'd start out in the second quest. That probably didn't help.

Little kids who don’t pay attention to the story, or adults who are aware of the series but have never played.

One aspect common to most Zelda games is an open world with no NG+. After beating it, you load back into to last save before the final boss fight. You are free to explore the world with all your equipment, and fight the boss again whenever you want. It was common for many kids to be introduced to Zelda in this state. You go to a friend’s house and load up a completed game with all items collected, no story or dialogue, and a big world to explore. All you know is you are controlling a mute elf with a sword and shield, and it’s called Zelda.

The original games let you name your character and didn't tell you the default name was Link anywhere in the game

IDK I've met a lot of people who don't play video games at all young to old, who thought Zelda was the main character.

If I were to say "no that's Link" they'd say they never heard of Link, who the fuck is Link. And it would spiral into a loop where I'd have to explain it again and they'd have a lot of trouble believing it or just stop caring.

I think it goes with if you see a box or game title with "ZELDA" on it, you naturally assume the main character is than called Zelda. Honestly some people don't care to look beyond that.

I definitely thought it up until the N64 games came out. I’d only played the SNES version as a kid and didn’t remember anything other than the gameplay.

Zelda is a pretty cool guy

I play tears of the kingdom with my 3 year old and he keeps refering to Link as Zelda. Every time. I keep correcting him but nope, we play as Zelda.

I mean, the first game kinda reinforces it by giving you more hearts if you enter your name as ZELDA. If you didn't read the manual, you'd never know Link's actual name.

Me?

Look, we don't all play pokemon.