What is our Human Purpose?

In science and religion, it is a true mystery on "why we are here"and "What is our purpose?" I don't know the answer, but I like to believe that we are here on this planet, by either "luck" or for a "purpose". We the human race, after many trials and errors of molecules and proteins interacting with one and another: we were formed possibly by "luck". Humans derived from less complex species, and therefore we are at top of the food chain and no  creature is higher than the human brain. In religion, Christianity offers us simple solution, God created man, and man is to worship God. I believe whatever the reason on why we are here, and our purpose, we are guests on planet earth. It is our duty, and responsibility, to clean the place we habit  and to maintain it.Regardless, of luck of just purpose, to preserve our planet for future generations. What are your thoughts?