I have a small scratch on the screen, I am very careful as well. It was usually in my front pocket with no keys etc but must have scratched elsewhere 😡.
If you don't like the idea of a case, use a screen protector to be sure.
If your going to cover it with a case and like to keep the slick look, have a look at the Orbino Strada Case. I don't like cases but the iPhone is so slippery I had to get a case for it.