I guess technically it would've been Pokemon but I didn't know it was an anime, or what an anime was, at the time.
After that the only anime I watched was Naruto, which didn't last long because I couldn't keep up with the Toonami schedule.
I got burnt out on the "genre" in middle school until one fateful Saturday night while I was half asleep the 4th episode of FLCL started on Adult Swim.
It felt like a fever dream, but I looked it up the next morning and it was real.
Had no clue what to make of it at the time, but I thought it looked cool and now it's probably my favorite series of all time, and now I also actually watch anime
The first anime i actually saw without realizing that it's an anime was probably Sailor Moon way back in the late 90's . Either that or Dragon Ball or Pokemon but probably SM was the first . Might've even been something else but idk i was in kindergarten back then so i don't remember a lot from these times.
The anime that actually got me into anime was Inuyasha in the mid 00's .
Pokemon (Probs everyone's first)
Yugioh DM/GX/5Ds I forget which first
Sonic X but I hated it
Dragon Quest Abel No Yuusha
Dragon Ball Z Kai was my first anime in that I recognized it was Japanese
Inuyasha, I was really stupid when I was young.
Then I watched Bleach, the anime where the main character can go one minute without screaming or saying his catchphrase.
Grand Teacher Onizuka and Mahoromatic (I almost cried fr fr) cemented my love for anime.