Let's assume that there is life out in the universe. Not that our existence is not already proof of that but the sheer number a planets offers infinite opportunities.  So let's pretend we all agree that there is life in the universe. Some are like us very young and incapable or traveling the Stars. Others may have matured or out of necessity figured out how to leave their star system. With all the alien ships captured on camera and throughout human history recordings of beings from the skies why have they not made themselves more publicly known?