The thing about mastodon is that it doesn’t have an algorithm to put recommended posts into your feed like the “normal” micro-blogging social medias you might be used to. By default, the feed shows only posts from accounts you are subscribed to in chronological order, so if you aren’t subscribed to anything, it won’t show you anything. You need to build your feed yourself by going out of your way to find accounts you want to see posts from.