Netscape 0.9 was released in October '94. IE was released in August '95 and the first version was just a licensed rebrand of Spyglass Mosaic (which despite the licensed Mosaic name was not a version of Mosaic).

There was a number of browsers coming up at that time, and Mosaic was if anything what drove much of that early boom, as the most successful option that led to both Netscape, Spyglass, and by extension IE.

Remember that Mosaic was readily licensed (and source available, though not under an open source license) - there were a number of other Mosaic offshoots (e.g. AMosaic for Amiga was released in December '93, with datatypes support)

Other browsers than Netscape around that era, excluding the text based ones, included:

* 1992: ViolaWWW (Unix; pioneered embedded objects, stylesheets, tables, client-side scripting); Erwise (Unix); MidasWWW (Unix)

* 1993: Spyglass (licensed the Mosaic name, but written from scratch; also the origin of IE), AMosaic (Amiga), Cello (Windows), any number of Mosaic licensees, Arena (Unix, Linux, NeXT; pre-release in '93; full public release '94; Arena was co-written by the later Opera CTO Håkon Wium Lie, and pioneered layout extensions that turned into work on stylesheets and eventually CSS)

* 1994: Argo (Bert Bos - co-creator of CSS; Unix; testbed for style sheets alongside Arena, and one of the first heavily plugin based browsers, with most functionality provided by plugins), IBM WebExplorer (Mosaic licensee); Slipknot (Windows; a really weird one which dealt with lack of SLIP/PPP connections by "hijacking" a Unix terminal connection, running lynx to retrieve the HTML, and then using zmodem to transfer both the HTML and images...)

* 1995: IE (licensed version of Spyglass); Grail (Python; supported client side execution of Python...); OmniWeb (Mac)

* 1996: Amaya (Unix, Windows, Linux, OS X), IBrowse (Amiga), Aweb (Amiga); Opera (Windows initially); Cyberdog; Arachne (DOS, Linux including framebuffer...; still updated as of two years ago...)

Netscape took a lot of users from various Mosaic licensees, like Spyglass, and browsers like Cello; had it not existed, sure, things would have looked different, but timeline-wise the gap was narrow. Many of the browser - like Opera - that launched after Netscape had started development before Netscape launched, and others were abandoned in some cases directly because of Netscape. Some were probably no big loss, but Netscape's brief dominance contributed to the near monoculture we had for many years.

There is no doubt it had improvements over Mosaic - I remember vividly the day the release with background image support spread across campus and every webpage looked garish for the next several years - but it was an advantage measured in months, and with competition heating up until Netscape stunted it for quite some time by becoming as dominant as they did until IE started catching up.

A lot of the things Netscape is sometimes remembered for were not Netscape firsts either, or areas where they necessary had a lead. E.g. client-side scripting, style sheets, etc existed before Netscape; work on CSS was ongoing at CERN around the time Netscape launched etc. At most things would have looked different, and maybe some things might have taken a bit more time without Netscape scaring Microsoft. But I also remember a lot of ire at how Netscape pre-empted a lot of standards at the time by just throwing stuff at the wall, and untangling the mess they left took years.