I've always heard that the JavaScript world was overwhelmed by far too many frameworks before jQuery became a popular standard for browser consistency, and Angular and React were the big names for frameworks and libraries respectively.

This isn't accurate - or at least your definitions/timing are off.

Back in the beginning of the web in the 90s, everything was done server-side in static pages.

Then with JavaScript (after 1995) devs could start sprinkling in some client-side scripting - rotating logos, accordions, etc... but browser inconsistencies were rife, si it was a huge ass-pain to support all major browsers. This was the era of (un-ironic!) "designed for Netscape Navigator/Internet Explorer" images on web-pages.

The next big leap was Microsoft inventing the XMLHttpRequest object that permitted "true" client-side web apps. This first happened in 1999, but they didn't exactly shout about it, and it flew under pretty much everyone's radar until around the middle of the following decade.

Next up devs started getting more serious about client-side scripting (especially given the possibilities XHR offered), and started writing libraries (not "frameworks"