I don't know that I'd start a new project in it, but jQuery has permeated the web to such a degree that I don't know if you *can* be a front-end web without being vaguely aware of it. It's worth *knowing about* but there isn't much to *learn* about it. It's a library for "querying" the DOM the way you do in CSS; that's why it became popular -- that particular task used to be difficult, even though now it's part of the DOM. I still use it for Ajax requests, mainly because the syntax is easier for me to remember than native JS. But most of what jQuery made easy is already easy in bleeding-edge browsers and frameworks. The rest - promises, events, animations, ajax - are sort of "helper fluff" that are also better done in other libraries, or native JS/CSS at this point.
TL;DR - Yes, you should learn it, but don't go out of your way to focus on it. If you understand modern JS & DOM techniques, then you'll be able to figure out jQuery easily when the day comes that you need to debug/modify/replace it.