Well, every instance has a "main" community that all users of the instance are sub'd to by default (if I'm not mistaken). Here on lemmy.camain its sidebar says
Since everyone on lemmy.ca gets subscribed here, this is the place to chat about the goings on at lemmy.ca, support-type items, suggestions, etc.
Was looking for a different community altogether and found this post.
I don't think it had been made at the time you posted, but as a heads-up, there's [email protected] for General Discussions now, in case you wanted another community to try to start conversations in!