I had a book on DHTML in the late 90s long before ajax was a thing. It simply meant scripting the DOM. The MS version did have some fancy transition filters too.
They were. Microsoft Outlook Web Access was exactly that, it's why Microsoft invented XHR. Google Maps later got a lot of credit for kicking off "Ajax", but OWA laid the groundwork.
While we’re narrowing actuallys, it was Gmail that got the credit. And somewhat relevant to the article, I believe that was Google’s first major showcase of the Java-based GWT.