Did anyone truly 'invent' the smartphone?
The smartphone is the sum of its parts. If you argue like I do that the sum must include a simple UI (i.e. touchscreen, not keyboard) a full browser (i.e. no WAP, but seeing the same view you do on a desktop browser) wifi (so you don't restrict what you do for fear of running up a huge bill) apps that can be downloaded over a network, GPS, and camera, then the iPhone (3G, not the original which lacked GPS) would be the first smartphone. They didn't "invent" it, they were merely the first to combine all those pieces into a single product - to see what the smartphone should be to have mass appeal.
If you use a lower bar, like "has apps" then it came about in like 2000 or so. But whoever created that first "smartphone" shouldn't be given any credit for inventing the category inhabited by the iPhone 7 and Galaxy S7. Those look and operate a heck of a lot more like the original iPhone than they look and operate like any phone that came before it.
Who invented the automobile? There are multiple people to choose from, but none of those early automobiles look or operate anything like what we would think of as an "automobile" today. i.e. IMHO you should throw out the early ones that worked on primitive batteries, steam power, used something other than a steering wheel to direct it, used something other than foot pedals to make it stop and go, etc. Those are not enough like a modern automobile to qualify as being their ancestor in the way the iPhone 3G is the ancestor of today's smartphones and not the first Windows Mobile 1.0 phone or whatever.