Alright listen. First of all you should not speculate on the value of things that you haven't done. Many couch-folk think climbing mountains is meaningless. But when you get up there, it sparks emotions and chemicals in your body that make you feel things you haven't previously felt. When you volunteer and make that kid smile, it sparks something. You cannot just speculate on the effect these things will have. There is a whole world out there, and the fact is that most of us don't experience much of it.
What you're doing is commenting on a blowjob's lack of biological utility, without ever having gotten one.
Second... Why is there not nothing? Idk man. Do you really think that's within our power to know? If you don't think so, then you need to give that shit up. If you do think so, then go for it. Figure it out.
You have an idle mind. It's the devil's workshop. I don't believe in the devil but this is a good quote. Humans are happier when they do things and affect the world, not just sit and think about it. Yeah that's just my opinion, but I've been through what you're going through. You just have to do a bunch of shit. You think you can just ponder shit and understand it. You can't.