Good ol' buttcraft 
I don't really mean in terms of mods, but like go off if you wanna. I'm a lifelong Minecraft enjoyer, played it basically from Alpha right up to release, and dropped off around 1.2ish. I've played it in bursts again over the years, but the more weird stuff they add the more weirded out I feel. I just wanna build houses with sloping rooves, sheesh... It does kind of make me wanna just give up and play Legacy Console on Wii U or something weird.
[Minecraft boomer alert I guess]
I don't totally hate what they've done with the game itself but it's clear that the launcher is a lost cause. Plus how does Java chug this badly on a Ryzen 2600? I have to choose between a performance mod that makes the game run, or pad support, because one of them uses Fabric and the other uses the other thing. Remember when Minecraft mods was just dumping .jar files into the game's directory?
I mean to ask, what is the way cool kids play Minecraft nowadays? Are there cool alternative launchers or modpaks or a specific version or whatever I can play that's cooler than Microsoft Occupied Minecraft and are more fun?
I'm really glad you asked this. I've got a couple of kids, all they do is watch Minecraft videos on YouTube. I've got a lot of computer hardware lying around, I'd like to setup an old school server for them to play on. Bought a copy of Minecraft way back when but with modern licensing and mojahn whatever I doubt I can even still use it.,, where to start?
If it's pre-microsoft and you haven't played it in a while, yes M$ took it away and no one has had any success in getting theirs back. You were "supposed" to transfer your mojang account to microsoft (and accept the new licensing) before a certain date.
If you just want vanilla or a few minor mods that's very possible, and I recommend papermc as the server. You have to edit just one line in the config file to allow "pirate" accounts to log in.
PollyMC (two Ls, no longer affiliated with polyMC(one L) (politics) ) is an open source pirate client that is as easy to use as the official launcher.
Or you could just play Minetest, a full free open source reimplementation of Minecraft with easy DRM free multiplayer in the first place.
If you need help with any of that just let me know.
You rule. Thanks you the advice!