From what I see, we are moving away from a heavy server which does the heavy lifting to thin server layers that just send data and feature rich UIs that process

From what I see, we are moving away from a heavy server which does the heavy lifting to thin server layers that just send data and feature rich UIs that process the data. This is possibly because the browser has become a widespread means of distributing general software. As a result, the domain of "backend" engineering has bled into the frontend and thus frontend engineering has gotten more complex. If you purely want to learn React in a way that allows you to do some light modification of an existing architecture then something like create-react-app or some browser codepens will be the best way to get involved with the library. Otherwise, if you want to understand React from a more fundamental sense, going away and doing some backend courses or learning some basic CS and/or FP architecture may serve you well in understanding the paradigms that inform React's design. As a bonus, these skills will never be useless. As for JS tooling, it's not ideal and is definitely a lot to learn all at once. Your best bet is to abstract over as much as possible and learn only what you need to when you have to. Though, again, the skill of picking up and using new tools is a valuable one in this line of work.