How was I not aware of this site? 😀 Direct download links and release notes for (almost) every version of Xcode released since "Xcode Tools 1.0". Of course, most of these won't run on modern versions of macOS, but it's still an interesting resource and I spent a little while reading through the early release notes.
Note: I did have some problems getting the links to work at first, even after signing in to the developer site. I eventually had to use a different browser and sign in to the Apple developer site, before clicking the direct links to make it work.