That being said not very many greenfield js projects in the last 5 years have brought in jQuery as a dependency and that's because (as others have pointed out) it's dated. Everything you can do with jQuery vanilla JS now does.
React is always a safe bet to learn, an amazing framework that has taken over professional front end development (for very good reasons). Some people will try to push you to Vue.js because thats the new thing (and it also is a very easy library to get started with) but if you're looking for having a new skill React can't be beat. (It still has more than 5x the amount of downloads per month than Vue.js)
However before you get into any framework make sure you know modern javascript.
jQuery is a DOM manipulation library, so in a sense it is lower level than React. It abstracts the DOM implementations across browsers to provide a unified interface. It lets you do things like animations, and find element dimensions in a cross-browser way.
Today, developers are choosing React because it more closely aligns with the needs of modern webapps. Most browsers have become more standards-compliant so jQuery is not such a necessity anymore. React is a fast and readable library to keep your page up to date with your data.
https://developer.mozilla.org/en-US/docs/Web/API/Document/qu...