CastleCrafters is a Java SMP on 1.21.11 and it is still really new. It is about a week old so it feels like you can jump in early and matter.
The server has a full economy so grinding has a point. You can sell crops ores and mob drops. There are also jobs that pay you for what you like doing like mining farming and fishing.
It is small and it tries to stay tight knit so people actually know each other. Land claims are on. Players are already starting to take roles and once player shops are set up it turns into real trading between everyone.
