> yet when JS gained that, with ES6, I could immediately "grok" what `class` and `new` was doing. I could never do that with __proto__ and prototype.
The new ES6 "class" syntax is really syntax sugar on the existing prototype system. "class" does not add new functionality to the language. Anything that can be written with "class" can be written with the older way. So really, you need to understand the prototype system to really understand how "class" works.
But I think you don't actually need to deeply understand how the prototype system works to use the new ES6 class syntax. Your "Java intuition" + the knowing that there could be gotchas in corner cases should suffice if you don't do anything weird.
The new ES6 "class" syntax is really syntax sugar on the existing prototype system. "class" does not add new functionality to the language. Anything that can be written with "class" can be written with the older way. So really, you need to understand the prototype system to really understand how "class" works.
But I think you don't actually need to deeply understand how the prototype system works to use the new ES6 class syntax. Your "Java intuition" + the knowing that there could be gotchas in corner cases should suffice if you don't do anything weird.