What were some ways old community sites grew before stuff like search engine optimization became prevalent?

Everyone else has already covered webrings and directories, but there's a couple things missing imo. Or maybe I just came in too late.

Back in, I want to say 2003 or so, I discovered this absolutely incredible browser extension called StumbleUpon. It was like a crowdsourced version of those contemporary curated link pages; you gave it a list of topics you were into (ranging from vague things like "art" down to really specific things like "), and when you pushed the "Stumble" button it added to your browser, it took you to a random website that matched one of your chosen categories. In turn, when you found a website that wasn't in the database, you could add it by checking off what category/ies it fit into. I spent hours a day hitting that button and being taken to random new content, and quickly became the clever one in my friend group by finding all the best "cheezburgers" and "demotivationals" and "image macros" lol. Hell, I'd still be using it now, if they hadn't shut down like five years back.

And let's not forget Geocities neighbourhoods! Every GeoCities site was a "house" in a metaphorical "city" and at the bottom of their page, you could move between "house numbers' to visit their "neighbours". So if you found a good site, but got bored, you might check out who's nearby. Cities were loosely themed, but didn't enforce topics of any kind, so you might go from a Sailor Moon fansite to a college student's tutoring homepage to a shrine to a dead loved one. You always found fascinatiing stuff eventually.