My first BBS was TOTSE, around 2003, not long after graduating from high school. Kind of like a chan, before 4chan, except everyone was namefagging. You'd see threads about John Titor and Timecube, people talking about doing drugs and dumpster-diving, and referring to themselves as SWIM someone who isn't me as some sort of legal prophylactic. The site the BBS was attached to was a sort of archive of '90s conspiracy theories, religion, esoterica, drugs, and outdated documents about how to defraud payphones.
It was apparently popular enough to have spinoff/revival sites, which I imagine is amusing to peruse if you've never read about "better living through chemistry" and such. It's hard to see the point in such an endeavor; people now give themselves over to mind-viruses, and everything triggers a canned reaction to whatever sort of "wrongthink." Even if they're not bots, they're not really any better.
I spent a lot more time on a BBS called "frostcloud", of which no trace remains. We mostly shot the shit about politics and philosophy. There was the resident anti-semite, who made absolutely every topic about jews. A canadian politician bantered with the guy and got canceled because his opponents construed something he said sarcastically as his actual view. There were mystics, musicians, cops, shitlibs, high school kids, a married couple of retirees in Britain. An affable "frottage" enthusiast— a western chikan, basically. You'd occasionally get blindsided by some turboschizo accusing you of being a jacobite and killing Angel Babies. A girl studying philosophy in the Phillipines complained about her professor demanding sex for grades. A junkie in Indiana got a mail-order husband from bumfuckistan who beat the shit out of her and, I presume, her daughter.
There was a healthy skepticism of the internet, which I imagine is pretty foreign to anyone born after 2000. The internet was for nerds, you're not really going to spend your time there, much less give a shit about what anyone thinks, right? It's the internet; it's not real. Then the internet was convenient for business, and facebook let you keep in touch with whoever the fuck, and then it was a necessity, and now you're born into this.
I remember a thread where we discussed what you think people sound like, based on their personalities in text and their avatars. It seems like that's the sort of thing that doesn't happen anymore— things shut down, you migrate to reddit or chans, and there aren't any avs and you the pool is so much bigger that you have to be really invested to recognize people from day to day. And even then, what "voices" do they have? Would you even want to know what some tiresomely web-savvy dweeb from reddit sounds like? It all homogenized and declined to the lowest common denominator.
I can't imagine such a thing existing again, not because the technology doesn't exist, but because people now are too conditioned into retard ideologies, with egos so frail that they can't encounter dissent without having a meltdown.
We got kinda close to an "old internet" feel in certain parts of Voat. There was /v/thedinnertable, where people tried to behave less like internet ghouls, which happens to be more similar to that aughts period, albeit in a self-conscious and semi-ironic way. It's hard to tell in hindsight what killed Voat: active subversion by those who didn't want to allow any escape hatch from reddit (which in 2014 had become fully converged) or the hyper-vigilant gatekeeping necessitated by the subversives. Either way, it wasn't conducive to the early aughts milieu.
Though, if the winged ape internet brigades have had their funding cut, maybe something like that could exist again.
8chan and Voat were killed off at about the same time, but have their sequels in 8moe and poal.
WinMX was a post-Napster P2P clients around the same time, in the early 2000s. It had what I guess was an integrated IRC server, where people made rooms about all sorts of weird shit. Even in the general rooms you'd encounter dudes who profess to be in a romantic relationship with a radio station, consummated by hooking his nuts up to the electrical lines. I feel like even perverts and weirdos have been reduced to the LCD of dog-rapists and child-groomers, lol.
I guess I'll also mention marginalia.nu, because it's probably the best way to find "web 1.0" documents. Not very stimulating, I know, but useful if you want a snootful of writing from twentysomethings who are now in their 50s.