A few things:
1) Its not water proof. Apple never claimed it was water proof. It is merely splash resistant. A couple of drops of water shouldn't harm it, submerging it on the other hand is a recipe for disaster.
2) The camera lens is sapphire. Sapphire is scratch resistant, but is more prone to shattering. As glass gets "harder" it becomes more brittle. The fact that you shattered your camera lens so easily proves that its sapphire.
3) The headphones are made form the same material that the last 4+ iPhone's headphones material. I have headphones from the iPhone 5, 5s, 6, 6s and 7. They are feel the same.