It's been two years since Salesforce launched LWC and looks like salesforce is not going to slow down.
LWC is also built on top of ES6 and my personal opinion is LWC is heavily inspired by ReactJs and VueJs.
If you want to master LWC I would say it's a mandate to learn ES6 first. Do not make the mistake of jumping directly on to LWC, the learning curve might be a bit steep and if something goes wrong you might even drop the idea of learning it, midway.
You can get access to it here.