I'm 27, I first visited 4chan when I was 15 or 16 in 2009 or so. I saw rage comics online and litrally just googled my way back to their origin and found /b/,
It was a unique feel. I have very vivid memories from my first few weeks on /b/. Everything was new, I only knew old bulletin board style forums before that. The interface was wierd, everything was super hectic and language was cryptic. I felt like an explorer discovering a hidden tribe, deep in the jungle with their own language and customs, I was genuinly intrigued what all of this meant.
Rolling quads to defeat ULTRA GIGA NIGGA? Wtf was a baaww thread? Why is everyone afraid of a shovel dog? Why was everyone taken out by candlejack? What's a roody poo and what's a candy ass? Why are we watching a webcam stream of a card stand in New York City and what was "oh-pee" (whoever that was) going to "deliver" there?
It was like a sensory overload and I felt like I just discovered a paralell dimension, far, faaar away from my rural German small town life, where the internet was still seen with scepsis by most.
In the following weeks I took a deep dive, just absorbing everything I could. I just had a lot of fun figuring stuff out. What seemed like an unsolvable mystery at first could be cracked by just lurking enough. The old vs. newfag dichotomy was extremely intense and rigid back then and people actually cared about not sounding like an utter newfag and I remember being actually nervous before making my first post ever. Oh the thrill! The edge and feel of it being "secret" and "forbidden" played a big role.
My sense for discovery dragged me deeper though. It didn't take long for me to find out that 4chan was just the biggest of the imageboards and that there's dozens if not hundreds of smaller ones. Some were just 4chan offshoots like 4chon.net, 7chan or 420chan but there were the many many national equivalents. sosach, Yliauta, karachan, dejimachan, britfa.gs, krautchan, brchan etc. etc. I visited them all and there, to my surprise and utter delight I had the same experience of early 4chan /b/ again: Completely different meme culture and lingo, their own insiders which took weeks if not months to finally uncover. I was basically high on internet culture and finding/learning about these secluded, underground communities filled me with happiness for some reason, it was my way to explore the world and feel like going on an adventure. being able to easily switch my demeanor to hide among the locals after just a few hours of lurking helped in my exploration.
I quickly ditched 4chan as my "homeboard" and went over to KC, the German equivalent. When 4chan scoffed at redditors being the uneducated, lowly outsiders and newfags, 4channers were seen as exactly that on these "deeper" boards. If you arrived there with 4chan lingo and habits, you'd immediately be outed as a filthy, childish 4channer who needs to go back ASAP. And thus my sense of conquering was triggered again. KC became the place of my fondest of memories of imageboard culture (between 2009 and ~2014). /b/ is really hard to explain because it really was strictly German only and the humour and community was a lightning in a bottle. /int/ was even better. A cultural juggernaut, considering gigantic sites like 4chan, >reddit

and today twitter are shaping most memes but the little international wing of the German 4chan copy birthed many a meme including wojak, countryballs, apu, spurdo, gondola and more. To this day some of these memes float around everywhere on the net and most don't even know what KC/int/ was.
Granted, Yliauta had a hand in many of these but the relationship between Yliauta and KC is another one of those deeply obscure bits of lore from the time back then. I couldn't really describe the dynamic between the two, you just needed to be there at the time.
I could tell many a stories about my adventures. Legendary threads people saved screenshots from for years to come, board raids and special events by the admins/staff, stuff like this.
But also just the every day 24/7 lurking was fun, there'd always be a surprise, a laugh, an insightful post. /int/ really brought people from all places of the world and all slices of life together. I kid you not that I got genuinely good life advice as a teenager there from some 30yo dudes that just shared their life stories and talked to us yunngins.
Then, slowly, change happened. As 4chan got more and more attention, the newfags trickled down to the deeper level of imageboards and they slowly but surely lost their own identity. By 2015, it didn't matter which altchan you vistited, the sheer mass of newcomers almost completely eroded the local cultures and everything read and felt like 4chan. 4chan coining the word cancer for people spreading the word about the place and drawing in too many newfags that diluted the culture was exactly that for the smaller boards. A giant tumor that smothered the identity of alternative imageboards. 4chan was the cancer.
By 2016 with the presidential election in the USA, the final nail was hammered into the coffin. 4chan was overrun by newfags, more than ever before and this wave hit the altchans as well. I can' speak for all of them but KC was basically culturally devastated. 4chan above all. The general tone shifted, too. Politics suddenly became a huge talking point everywhere and now there was no coherent community anymore but just the same fractured americanised politcal lense on the topic like everywhere else in the web. "Shills" were now suspected around every corner and after the election everyone suddenly was a /pol/tard. While I would consider the election and Trump's campaign a gigantic highlight of chan culture because - let's be real - all the memes were big fun and the atmosphere, mood, yes even aura on the day Trump won was magical. It was the last time we did something "FOR THE LULZ!"
Then I kinda just grew up. Not only was I bored from what I saw every day on the chans but I just didn't have the time to mash F5 all day on 3-4 different boards anymore. I also became disenfranchised. By 2017 I felt like barely anyone even remembered the "good old days" (or what I considered them to be). If the statistics could be trusted, among 1000 anons, maybe 1 started lurking 2009 or before. All these people were essentially strangers to me who didn't appreciate the same things, didn't remember the same things, didn't want the same things and whose "good old days" were times were when I already started to miss my "good old days".
2018 KC went offline. Admin just didn't care anymore. It was replaced by Kohlchan, a very cheap copy made by people who came long after KC's glory days and couldn't even try to imitate the glory of KC because they weren't even there to witness it. Both /b/ and /Int/ today are entirely worthless.
4chan's /b/ at this point is also completely dead, reanimated as some eerie zombie. /b/ Wasn't the cultural hub of 4chan anymore. For me, 4chan/b/ was THE entryway to imageboard culture. Now it's just a place where horny idiots dump nudes of their ex gf.
Themed boards like /v/ and /tg/ are a story for another time but in short, they got hit by the same waves.
Today, I just check by now and then, mainly when something big happens like the Ukraine war or an election or something, just because imageboards were always very quick with everything so it just became habit. Especially back then it took the legacy media an hour to even report an event while you could already see unedited photos/videos of everyhting that happened on the imageborads.
Culutrally I feel 100% disconnected from the current, average chan user. They're like little children to me, I can't make sense of what they're saying but I also don't even care.
In 2009 I was the child and the "adults" were talking in too complicated words for me to understand and I wanted to be one of the cool grown ups and thus adapted and learned. Now, I just don't care what the kiddos are babbling about this time. I've seen it all, it's all just repeating cycles, even the memes just fill the same niches every time, they just get a differnt coat of paint.
There is also absolutetely 0 sense of community. It just has gotten way too big. What once was an "us outsiders and lowlifes vs. the world" is now "me vs. you"
It was cool while it lasted. Defintely a unique time that already today some people can't even imagine. Since barely any archives exist from back then if at all, it's also more or less completely lost and word of mouth like mine is the only way to even learn about most of this stuff.
My biggest regret is that I never kept a good and organised folder. In the last 13 years I lurked from several PCs, laptops and later phones and rarely even bothered to transfer my lurk folders so unfortunately there isn't one giant archive of memes and screenshots from the last 13 years of chan experience.
P.S.:
moot leaving 4chan also plays a role I forgot to mention. Admin/Staff involvement was a 4chan staple. 4chan/b/ had so many goofs and special events where moot or the mods decided to do something fun and you'd actually SEE moot and mods post now and then, I remember moot just casually replying to one of my posts one time.
4chan's staff today is like a black box. They have no face, no interaction, no community events, no public bans with funny ban messages anymore. You have this giant imageboard with huge cultural influence (that's waning btw) and you don't even know who runs it anymore. Hiro is like a ghost, the IRC is now hidden and /qa/... well. it's getting late.