I am not doing anything special but I do inform our community (“mankind”) for 25 years… And I feel useful because I am good at it.
“Mankind” can be a group of other people.
Edit: What people value the most? Compliments. So if you are useful and receive compliments, you will eventually be happy. But ofc you can be happy without being useful, for sure.
Fun fact: I've built something very much like this that powered a number of programs that I sold over the years and it was written when I wasn't nearly as good of a programmer as I am now (take off 30 years of additional experience). If I look at OP's code there are a whole raft of nitpicks but there isn't anything immediately and obviously wrong with it and just speaking for myself, that is surprising because most people's C code is - and I'm being generous here - absolutely terrible. This has potential, but I'd have to really dig in to see how solid it is and I don't have time for that right now, but I've seen far worse code than this.
Least surprising thing you've said so far.
but I do inform our community
Inform them what? "You there, this project you've worked on, learned from, gotten joy from, been complimented on by your peers...I, with my 25 years of peerless wisdom, find it useless and you should feel bad for doing it"?
Sure...you're a real people person.