Are you sad because your open-source project didn't get traction?

That happens all the time with most people, I guess. Someday it may attract some people, but it is not a "fair" game. Chance matters a lot.

I have at least 10 libraries on GitHub that I think should have gained some visibility, but didn't. There are thousands of similar cases.

I suggest that you keep the idea machine on and keep building stuff.