An age old question, that drives so much human energy to explore and understand. From religion, to work, to family, to friends, to pleasure, to exploration, to discovery, to ambition... much of our lives are spent in search of a meaning for life itself. Is there a reason behind our being?
The purpose of life is happiness
The purpose of life is survival
"Survival of the fittest" is a common phrase in the biology field. If humans are not intent on their survival, they will go extinct. Similar to other species, humans eat, drink, and avoid danger their entire lives to stay alive. People spend their days making sure they survive to live another day; that is the sole purpose of life.
Evolution is a conquest of survival
All life forms on earth have had to evolve and modify their DNA in order to survive, something which is indicative of the desire of life to sustain itself. Thus, the purpose of life is more primal and species are entirely concerned about ensuring they remain competitive in the ecosystem.
Procreation has been the driving force between human interactions for centuries. If people did not procreate, they would not exist. Therefore, the purpose of life is to procreate and continue giving life to future generations.
Procreation is a defined property of life
Without procreation, a species cannot continue living. As a result, procreation is the purpose of life.