It sounds lame and normie af, but simple politeness goes a long way. I think a lot of people want to log on to their preferred social media and pal around with their community (here, or wherever else), which is all good and fine. I recognize that if everyone commented on here as though they were at work, it'd be boring as fuck, and it'd feel pretty damn distant and not like a community at all.

I think that a middle ground would be to imagine that you're at you're local pub or something. Your buddies are gonna be around, and some folks are gonna be kinda drunk or whatever, but you gotta remember that you're still in public, and you don't know everyone who can hear [read] what you're saying. The pseudonymity of the internet and sites like this have stripped a lot of the indicators that would remind us of this away. We obviously don't see each others faces as we post and discuss with each other, you get a name and that's pretty much your entire identity.

If we want this to be a community, we really should start acting like it a bit more. People talk about how they want this site to be a part of an "educate the libs pipeline" or whatever, but you end up with dunk-seeking behavior from Twitter, or debatebro behavior from Reddit. It's obnoxious, and anyone who casually drops by is likely to either be turned off by it, or they're going to like it and want to participate in it. Neither of these builds a community, much less a forum where you can help curious minds grow. Memes and dunks are great spectacle on major platforms where 100k people are going to see it. A site with 12k users and a small fraction of them active is going to need to take a different approach.

Edit: I realize that my post doesn't directly answer the question directly, but I guess my hope would be that a change in atmosphere would be a productive step toward an environment that feels more welcoming overall.