There were loads of Symbian/S60 phones with browsers.
2.5g/GPRS was usable enough at the time.
WAP was more 1999, a lot happened between that and the iPhone.
I’m not saying the iPhone was the first phone with a web browser, I’m saying that it was the first phone with a web browser that was good enough for average people to want to use it.
Clients were lining up en masse for iPhone-compatible websites, but none of them ever cared about S60 compatibility.
Symbian phones were also based on WebKit, however it wasn't nearly as usable due to many factors, mostly because it emulated mouse pointer (and you controlled it via the joystick) and didn't provide the pinch-to-zoom fluidity of the iPhone Safari. Also iPhone supported most of the major fonts used on the web, had font smoothing, etc. I've used both Symbian WebKit and Safari on first iPhone, and they aren't even close even though they're based on the same underlying browser tech.