There's absolutely no reason to believe that considering those APIs add new features independently of each other. A library like jQuery can serve as an intermediary if browser A implements new feature X that is possible in browser B but through excessive (and slow) DOM manipulation.
jQuery can act as a bridge between the time browser A's implementation and browser B's.
There's not much added to the browser that's particularly independent (i.e browser A adds it with browser B having no plan to implement it at all), and when there are APIs that are perhaps newer and not widespread yet, it's usually easier to pull in a specific polyfill (or ponyfill) for that specific feature, rather than rely on one library that's trying to cover everything. Especially as those libraries tend to mimic the API as it is expected to be standardised, rather than implementing a distinct API as jQuery does.
In practice, I'd much rather use the native APIs to do things in the browser than a wrapper library, because I find abstraction from these wrappers tends to get in the way as often as it helps. With modern JavaScript (for-of, the spread operator, far more array functions), it's usually only one or two lines more code to do things the native way, and I find it saves me a lot of complexity down the line.
> There's not much added to the browser that's particularly independent (i.e browser A adds it with browser B having no plan to implement it at all)
You haven't seen the privacy nightmare APIs Google is trying to push on web "standards"? The only other two browsers, Firefox and Safari, are not going to implement most of them in the foreseeable future.
Unless something has changed about jQuery, it is only concerned with DOM manipulation and data fetching. Do any of the privacy nightmare apis touch those areas?
There's absolutely no reason to believe that considering those APIs add new features independently of each other. A library like jQuery can serve as an intermediary if browser A implements new feature X that is possible in browser B but through excessive (and slow) DOM manipulation.
jQuery can act as a bridge between the time browser A's implementation and browser B's.