Straight from wikipedia: "the device would require a triple layered capacitive multi-touch touch screen, a very new and advanced technology at the time."
The innovation was making the screen the only interface you needed, by pushing the boundaries of what it could do. There was no way to make screens do anything like this in 2001, when PDAs were around. By 2005, the tech was still advanced but mature enough to exploit it, and Apple did it to the fullest.
While I couldn’t find (while zapping some food) who innovated the screen on the iPhone 1 I’m not sure Apple did and neither did you prove otherwise (burden aside)
The innovation was making the screen the only interface you needed, by pushing the boundaries of what it could do. There was no way to make screens do anything like this in 2001, when PDAs were around. By 2005, the tech was still advanced but mature enough to exploit it, and Apple did it to the fullest.