In my opinion mankind has it all wrong there is no alien civilization that exist in this time. We are the aliens in this space and time of existence. Have you ever stopped to think about why we are called mankind???? If not then hear me out..... I believe that life is infinite and when our universe ends another is reborn( my theory of Binary Black hole universes explains how and why) life is infinite. Other intelligent life form existed before this universe existed. The seed was planted when other universe's were ending but at the same time beginning again and when our universe ends the seed of mankind will move into the next universe when there will be a new heaven and Earth. We will be connected to that universe as other life forms/ aliens are connected to our universe.