Dear Avira,
Just for fun, here is a different argument. It used to be thought that the world was the center of existence. Now it is known that the universe is far more complex and much larger than we could comprehend. Yet, we are undoubtedly very much here and alive. In all this complexity we (humans) are very much alone. Alternatively, within the complexity there exists parallels that are similar to us. Since the purpose of all this complexity is only known to Hashem, He alone knows what the use of alien existence is.
The only dogmatic claim I would make is that if there is intelligent life forms, they would have been bestowed some form of revelation.