Exactly, there’s nothing inherently boring about being earnest. You can be earnest and boring but you could also be earnest with a good sense of humor and an interest in film history or software engineering. I’m not going to go all in on pg’s earnestness essay but it’s a positive trait and if you have genuine interests, there’s a good chance being earnest makes you more interesting when discussing interests because you are less likely to be invested in impressing other people with your interest. If you’re earnest your interests tend to scratch your itches of curiosity. But if you are earnest and uncurious then yes you may be boring.