The main body of the iPhone Air is thinner, of course, but including the camera bulge, I think it's thicker than all non-pro iPhones up to the 16.
Is there something about making the main body thinner that makes the iPhone Air more comfortable to hold than other smaller phones? Is it the weight? The 17e is only 4 g heavier than the Air, and the 16e is only 2 g heavier.
I have never been interested in the Air because of the size, so I can't even remember if I have picked one up in an Apple Store.