http://yuiblog.com/blog/2006/02/13/the-yahoo-user-interface-...
(I too am old enough to remember the internet before the web. You really had to work hard to goof off at work when all you had was nntp, archie and gopher.)
Nonsense, I could goof off quite easily with nntp :)
And I still miss the spinning globe.
Here's a whole list just for click, which is probably the most standardized event handler, and doesn't even go back before the IE5.5 era:
The other thing it did well was change the thinking about how JavaScript should interact with the DOM. In the past you'd have libraries that made DOM access easier, but they largely followed the same conventions as the underling APIs. jQuery broke from that and completely re-envisioned the API layer. The underlying APIs were treated as an implementation detail; this approach is something that subsequent libraries have adopted too.
jQuery was a huge timesaver, as was dojo, mootools, prototype, etc and not having at least one of these libraries would have sucked. And although jQuery "won" it could have easily been any other javascript library.
Even if these libraries somehow didn't exist, there was tons of cross-browser snippets plastered across the web that dealt with most of the common problems (ajax, event listeners, etc).
Prototype first came out in Feb 2005. Dojo 0.1 was Aug 2005, and 1.0 (first stable, after a total rewrite) was Nov 2007.
I do remember using Prototype with script.aculo.us and thinking it was pretty neat to add some effects to my server-side-created web apps, but that they'd largely stay server side. The first time I saw jQuery, that was when I thought "Yeah, okay, we can actually start building some serious client-side interactions here" instead of just server-generated HTML pages.
jQuery took me from hating (but tolerating) javascript to actually enjoying client-side web development.
jQuery is pretty much the only library or framework made 10+ years ago I can use and still feel like "this is actually well-designed". Frameworks generally obviate the need for it, but if a framework isn't an option and if I'm going to be writing more than 100 lines of code (otherwise I'd suck it up and use plain JS), I always still use jQuery.