The complexity of the universe is beyond human’s imagination. There are millions of planets like the earth; possibly there would be life as well.
The plantation of consciousness (or aatma) in a body, whether human or animal, insect or a bird is a mystery. Science has its own theories, however, it often falls short.
No one knows how this universe works, but because of our limited knowledge, we believe what we see. It’s like a frog in the well who believes there is nothing beyond the walls of the well.
Who knows if the earth is the hell for other planets! Should we be happy or sad when somebody comes or goes from here? I am not sure.