True. The lens is round because it actually takes a wide spectrum and centers this to a single smaller point.
While possible (now a days) to make a round censor it wouldn't make sense do this as all screens and picture frames (with some exceptions) are rectangle or square.
the camera is a circle because the peripheral vison is better in order to get a better picture, then it is converted to pixels and made into an image, the image is a square because that's how the phone can present it, and that's how the pixels work