The meaning of life is debatable over the different species of life. There shouldn't be one fixed definition. In my opinion, I believe that humans serve to replicate over worlds in an effort to make the said worlds uninhabitable so that nature can redesign the said worlds to fit in to its' genetic destiny. So in effect, human beings are nothing more than highly developed, autonomous virus cells that belong to the mass intergalactic virus called le homo sapien.
Whereas, viruses that humans contract are really a planetary anti-virus, or anti-biotic.
But then again, the meaning of life could also be for life to spread throughout the cosmos in order to justify natural existence.
But then again, the meaning of life could be to die.
But then again, it could be that we don't actually exist, that we are apart of a collective conscience and serve as its' thought processes. Heat death could be simply explained as an idea being discarded, and big freeze could be an idea put on hold. The big bang could be the creation of the said idea, whereas the big crunch could be the closure of the said idea, and if this is true, than most likely the universe would go through a loop of big bang, then big crunch, then big bang, etc, meaning that one idea ending could be the birth of a new idea. The big rip could be a migraine. See what I'm getting at? Our existence could merely be an unconscious imagination of someone who actually exists. Therefore, the meaning of our existence would be to create solutions for the said host.
Savvy?