Some relevant answers at hashnode.com/post/should-i-learn-reactjs-or-jquer… and hashnode.com/post/in-the-era-of-es5-and-es6-would…
But the tldr: learn ES6/vanilla js first; and then if you need to work on legacy systems that use jQuery you'll end up learning that as well. But be aware both are standard DOM and quite different from the "virtual DOM" of, say, React.