Humans are pattern recognition machines - We are exceptionally good at it. We see a pattern and it jumps at us and starts engaging all of our senses. That is why clouds look like dragons to us, why the rustle of leaves can sound like whispers, and why we have our "Lucky shirt", just because a nice thing happened to us twice while wearing said shirt, and we immediately saw a pattern. The same thing, only on a much more intense scale, happens to us with faces. If you thought we are good at recognizing patterns, That is nothing compared to our ability to recognize faces.
Our brains are so hard wired to look for faces, that whenever we see two circles and a line, our brain immediately screams "FACE!" and he starts deciphering what that face is thinking and feeling. That phenomenon is called Pareidolia and it is the reason why we see so many faces in places.
