Just like reddit, you gotta get off the default main pages. Go to browse.feddit.de and just start looking for communities that interest you. When you find one, tab over to [your.instance]/search and paste its URL or name (it’ll be formatted like !communityname@instance.bluh) into the search bar, click “sidebar” then “subscribe”.

After you’ve joined a number of communities, you’ll start seeing a more varied bunch of stuff.