https://github.com/jquery/jquery/blob/3.0.0-rc1/dist/jquery....
I'm a web dev for 10 years now and never used jQuery directly. (I used Ember for half a year, which seems to have jQuery as dependency)
I'm also not sure I'd call document ready the most fundamental as a lot of people (including me) used to use onclick='' and onload='' directly on elements back then when we all loaded script tags in the head.
But I didn't hit them, because I mostly did everything on the server side.
When I switched to SPAs, I used ExtJS.
To me it always felt kinda strange seeing all these jQuery Stackoverflow questions and answers.
When I switched from server side rendering to SPAs, I had the impression everyone was already hating on jQuery and avoided it. I read "Pro JavaScript Techniques" and "JavaScript the good Parts" and started my JS career :)
ExtJS 4 came out and I did my first SPA with it.
Later I did some university projects with Ember, which seems to use jQuery, but I never had to call one of its functions directly.
After that I started freelancing and ended up in a React project, which I found kinda nice to work with.
Then ExtJS, then a short stint with Ember and after that React.
I started with learning vanilla JS and doing my professional stuff with ExtJS.
But as you say, jQuery wasn't a requirement. I knew a few people who hated it with passion back then, they were all using MooTools. That's probably why I avoided it...
I only used ExtJS 4 and 4.1
I liked their API documentation and the xtypes that allowed for declarative Views. React reminded me of this later.
I read about those problems.
First they changed the license then the switch from 3 to 4.
This cost them many customers.
I started with 4, so I didn'T encounter these problems.