Feature phones could already do what the iPhone did (and in some cases even more). Multi-touch devices were available before the iPhone. PDAs had also been about for years and did everything the iPhone could do and more. And Android wasn’t far behind the iPhone and also improved upon the original iPhone.
In fact the original iPhone wasn’t even that good compared to the competition. It was lacking a lot of features people considered “must haves”. Native applications (everything was web apps originally), copy/paste, the ability to background applications, etc. And Ballmers point about the lack of a hardware keyboard was absolutely right for that era.
Apple have successfully rewritten history here, like victors often do. And so people often credit the iPhone as being uniquely revolutionary. It certainly was industry changing but it wasn’t singularly responsible for that change.
I say this as an iPhone user with an Apple Watch and other Apple hardware. So I do buy into the Apple ecosystem. But I’m also an old fart who has lived long enough to have first hand experience, both as a user and as a software engineer, pre and post the iPhone.