Very similar boat for me actually. First game I ever "played" was
on a proper cabinet at a laundromat with my dad. As in I actually watched him play as he guided my hand on the stick.
Melee was the first game I actually played but only for a few minutes as I was content to just watch since I didn't really know how to play. I was familiar with Pokémon due to the anime, and I'd seen Mario 64 being played at a friend's house.
Brawl was my actual, proper first Smash game and the first* (aside from Wii Sports) game I had for the Wii, which was also my first console. (Played a lot of my sister's PS2 prior to that though.)
So aside from the very brief moment with Melee, Brawl was my first introduction to the vast majority of Nintendo's library. Learning who all the characters were and then actually getting into their series later down the line was one of my favorite parts of the experience, not just for Smash Bros. but for video games as my hobby in general.
While I'm sure there are plenty of others who went on to have similar experiences with Smash 4 and now Ultimate, I do think it's pretty unfortunate that so many people (at least a lot of the really vocal ones who participate in Smash discourse online) seem to be averse to actually discovering/learning about characters/series that are unfamiliar to them. I know it's likely a vocal minority too, but the focus seems to be almost solely on the biggest names possible now with smaller series having been all but abandoned outside of a few diehard supporters.