My memory there is a bit fuzzy, but saying there was no official Mozilla web browser feels misleading. The Mozilla Suite (which I used for a while even in the 'milestone' versions) contained a fully functional web browser, Navigator - it was just really heavy and cumbersome because it also had the mail client Communicator and the other stuff like the IRC client and it was very new, very raw, rough-edges software built on this new XPCOM stuff. Very 'kitchen sink', inspired by the Netscape 'SeaMonkey' suite (SeaMonkey I believe lives on under that name). It wasn't based on the OG Netscape source code very much at all - while an attempt was made to develop that, it was so bad it was basically thrown in the bin and rewritten from scratch - which is where Gecko comes from.

K-Meleon and so forth was an attempt to take the core Gecko components out of the Mozilla Suite and just have a small simple browser built in it. Having seen that and a few others which had the same kind of idea but were native, Phoenix, which became Firebird, which became Firefox, was... kind of a grassroots disruptive community effort to try the same sort of minimum-viable-product browser thing in XPCOM as a cross-platform experiment, which rapidly gained adoption when people started realising how much faster and better it was to build it that way from the ground up instead. It certainly didn't feel like it was "AOL Time Warner" sponsored. If anything, it felt kind of chaotic. Nobody did a detailed name search because it was an experimental side project.

That worked so well, Thunderbird the email client was forked off too (during the Firebird era), and if I recall Sunbird (the calendar part)?