I personally believe that because our universe is so large we can't be the only ones.
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We're likely not the only intelligent life out there but seems more probable there are more life forms like bacteria than humans. I doubt any intelligent life forms like us ever have visited earth or ever will. The universe is just too big and we are so far away from being able to exit the milky way let alone visit another galaxy. Any communications via radio will be hundreds if not thousands of years old due to vast distance it has to travel. We are alone in our little corner.