I agree with this notion. However, it is concerning that jQuery hasn't had a release in 12 months:

https://github.com/jquery/jquery/releases

You failed to notice that they committed less than a month ago to their master branch and approved several PRs.

Their last dotX release was also 9 months after.

You should also always have a look at roadmap (https://github.com/jquery/jquery/wiki/Roadmap) if you are trying to get a read on any project's longevity.

It is in a way a good thing that a mature library like jQuery isn't released too frequently because all the websites that use it works just a little bit snappier because jQuery is usually already available in cache in the browser from some other source and if not, then the nearest CDN probably has it.

On the jQuery website, the latest download version is 3.3.1.

http://jquery.com/

On GitHub, it says that 3.3.1 was released January 20th, 2018:

https://github.com/jquery/jquery/releases

Releases matter, as that is what gets the changes to end-users, and infrequent releases typically indicate a stagnant project.

I am not trying to disparage jQuery, rather the opposite, since it is mature and reliable software. Open-source projects, like houseplants, need stewardship, and jQuery (along with other JS Foundation projects) may be overshadowed by JavaScript ecosystem hype-cycles that are competing for mind-share.

At this point, jQuery is more or less considered 'conpleted' software. It's very mature, and works well.

Why??? jQuery is so old, I expect it to be “done”

As stated above, open-source projects need stewardship. Otherwise they languish. I genuinely hope for jQuery to continue as a project and community endeavor.