This is probably one of the most stupid things I've ever heard. The reason why it couldn't have been created by nature is that nature would have no reason to do so. Sure, nature would've been able to shape the rock, but the rock's shape makes no sense to nature itself, it only makes sense to us silly humans, which is why we're the only ones who can make it. Nature just does what's natural, and it tries to reach a balance. It does not actively work to make the world look pretty or to shape things to certain figures for purely cosmetic reasons.
So you go directly to calling my examples stupid? If making humans makes sense to nature than why not make humans on a wall? Your argument is saying that nature has a mind, therefore being a god of some sort. (The heathens of old worshipped nature)