It was a full unix OS, not some mobile-specific trash like the others (Symbian, Windows Mobile, Blackberry). Capacitive touch wasn't an invention, but a premium form of touchscreens (most were resistive).
Having nearly 60fps high quality 3d accelerated animations on a phone also contributed to a heavily premium feeling for the software. It enabled things like Inertial Scrolling, which among other things (like first class typography afforded by using OS X, and a fully standards compliant web browser), none of which were "innovations" in the sense of "we came up with this first", but more exceptionally good engineering in service of a great experience.
In almost every way (apart from the "traditional phone metrics" like 2G ironically), the iPhone was a huuuuuge leap forward from the status quo.
It might be true that anyone else could've done it. But nobody else did. It wasn't just luck that Apple did.
The iPhone was the first one that I actually used to take pictures and play music. It wasn’t the first to have those features (and the edge network was super slow), but that polished experience is what made it work. And made it clear to everyone how we would interact with phones for decades to come.
It was a technological inflection point. That’s why it is looked back on the was it is.
There was a "cult," all right. It consisted of people like Steve Ballmer plugging their ears, shutting their eyes, and denying the obvious.
Yet we're supposed to give to consider the iphone a revelation because of multi touch. I had the iphone 3g. It was a more polished experience than other phones but that revelation part was just not there. Apps made it big, later.
I swear people treat iPhones like a cult.