I started a while ago when I was young with some hand-copied extract from AD&D2 copied from the notes of my friends who copied-it on photocopies from his friend with tons of house rule/homebrew at each copy.
Then, played a lot Warhammer FRPG, and finally got some money to buy Nightprowler a french game about thieves in a large city.
...1981 moldvay red box was my first product, but the first i played i think was 1977 holmes, although i don't know for certain because i never saw my cousin's books; in fact, i've been unable to identify which module he ran us through to this day...
DnD 5e which then turned into Soulbound which then turned into a TTRPG convention when turned into backing games on Kickstarter and buying other systems.
The first system I played was the D&D Next playtest but the first rpg product I bought was the Shadowrun 5e corerulebook. I never actually played it and it seems too complicated for my tastes now but I still have the book.
I think it must have been Xananthar's for D&D 5e. I'd been playing for ages, but that was the first book I wanted a physical copy of. I have a copy of the Player's Handbook as well now, and more recently, I bought the FFXIV TTRPG, as well as the Star Trek Adventures: Lower Decks splatbook. Everything else is digital or improvised
I got the D&D 3e books when I was a kid. I completely, deeply, uncritically loved them. Read them cover to cover. Spent a lot of time drawing nonsense dungeon maps and coming up with terrible ideas.
I remember I went to some game shop in some local mall and asked the guy for advice. He was like, "yeah i don't know, but that guy's into it" and pointed me to some customer who was a mega D&D nerd. He was surprisingly patient with my youthful excitement. I remember being like "So I can just... do anything in the game? I can be like, you kill the orc and his eyes are magic??" The guy was like ... i can't remember exactly what he said, but it was something like "You can, but probably don't spend a lot of time on minutia. You probably don't want your players spending 30 minutes checking every single trinket and orc body part for secret magic."
I don't really like D&D/its close relatives much anymore, but like many people it was my entry point.
It was a game called The Dark Eye (https://en.m.wikipedia.org/wiki/The_Dark_Eye_(role-playing_game)). It was weird but fun, and my first foray into ttrpg as a kid. After that I got into AD&D 2nd edition (with the weird backwards THAC0) and also Warhammer 40K (2nd edition). Yeah, I'm really showing my age here 😄
My father started us on the first edition of the Dark Eye (from his own uni days). I started to play that with my friends when I was about 16. Another friend borrowed us his books for the fourth edition. The first books I bought myself were the revised fourth edition.
Dnd 5e. It was my first system I played and then got the PhB. Then did a bunch of 3.5 and pathfinder 1e before moving back to dnd 5e. I have done most of my time in 5e but read a lot of different ttrpg that I haven't gotten to play yet.
I started with Robotech, then I worked up to Rifts, and Shadowrun. I didn't jump onto the fantasy-only train until Stranger Things got a bunch of my peeps into TTRPGs.
Call of Cthulhu sourcebook (Ed 5.6.1) and a set of dice. Bought from a little shelf of RPG books at my local comic book shop. Was also the first system I played.
friend had the boxed basic dnd where race was a class so you could be the fighter, cleric, magic user, thief, dwarf, or elf. something like that. Im not sure we were not even playing it right. I swear star frontiers may have been the second one.