I think you are scratching the surface of a really interesting anthropological phenomenon here. As a species we have evolved an adaptation by which we insert fictional constructs into our understanding of reality. These constructs, myths, stories, superstitions, religions etc have always been a response to the anxiety we seem to experience around the unknown. Although we recognise it as fiction, science fiction is still part of the legacy of drawing beasties on the edge of maps to indicate that beyond the known was the exotic. However we really do know better. Using statistics and our understanding of life and evolution we can fairly safely conclude that there will be living microbes in salt water aquifers on Mars which will be distantly related to primitive earth bacteria. We can also conclude that Mars is made of fairly standard reddish dirt and will never sustain human life. Further conclusions based on statistics and evolution would likely be that intelligent life beyond Earth will look and sound like us: warm blooded, hominid type species that evolved on planets with molten cores, ice ages and fossil fuels. For example Jame's Cameron's Avatar presented a fanciful world that ignored basic evolutionary principles: a four legged body schema will always outcompete a 6 legged one because four is just as stable but 50% more energy efficient - because six legs requires 150% the energy intake that 4 legs does. The most interesting possibility I have considered that we might be missing due to our own story telling about ourselves is that our species' ecological purpose may just be to be the biosphere's response to global cooling.