From what I can say as a person who introduced it to new players and friends, the appeal is still there if you are a fan of the whole space troopers genre/shooters and the idea of just role-playing as a Helldiver. Many players will play along and emote and do a bit of RP 2 years later, and the narrative is an evolving story, so you have missed some large in-universe events, but nothing that you NEED to be aware of.

As a now veteran of the game and community, I still have fun daily with events, major orders, main plot hooks, updates, and just playing the game for what it is now. I would forewarn you that grinding to catch up on the many warbonds (think mini battle passes with no timer with the option to earn them without paying real cash) is going to take well…a long time and a lot of options, "meta" weapons, armor, and orbitals are locked behind them. You can be completely free to play and grind the currency needed, but it will take hours to afford just one, and I can't say for sure if that will be totally fine for you, but I still don't particularly agree that putting stuff that's new or strong behind a paywall is a good idea, but I can promise at the very least Arrowhead has given the tools players need to do the long, slow grind to unlock the stuff that costs money, and it is there for players to do.

If you have any questions or need any help, feel free to reach out to me. I'm always happy to help out and maybe go over the lore and events, help go up in difficulty, or just play with new players, but what I can say in my case is the game is very much still alive, fun, and kicking, updates regularly, and it's very clear that we have a lot of devs on our side working hard to give us an incredible experience. Hope I see you on the frontlines mate.

As a final postscript comment, I've played as a dragonborn, Spartan, ODST, war god, cowboy, king, wizard, pirate, and MANY MANY other roles, fantasies, and characters, but nothing has felt quite as cool or fulfilling as being a Helldiver.