Knife, pen, pencil, paper, book I can get behind. The rest seem to be less a case of being "so well designed you don't even think about them" and more a case of

Knife, pen, pencil, paper, book I can get behind. The rest seem to be less a case of being "so well designed you don't even think about them" and more a case of being "so elementary there's nothing to think about". A cup is a receptacle. So is half a coconut. A pillow is a soft thing to recline on. Also, I really wouldn't conflate/group pencil and pen just because of their similar purposes. They're very differently designed objects with a good deal of complexity to each.