You don’t have to create a user here if you’re already active elsewhere in the Fediverse (Mastodon, Lemmy, etc). Through the magic of federation, you can follow communities here and interact from your existing instance.

For example, on my Mastodon account (@neilcar@infosec.exchange), I can search for the URL to a community here like https://lemmy.cloudsecurityofficehours.com/c/csohtopics. This will bring up the community where you can follow it, which will put all the posts and replies in your feed. If you reply to something, it’ll show up in the community here.