The purpose of life has been an eternally multi-faceted philosophical issue. From an objective and evolutionary point of view, procreation is a defined property of life, so it is the purpose of life.
The seven key defining features of life are organization, metabolism, homeostasis, growth, reproduction, response, and evolution. Of these seven characteristics, reproduction is paramount as life cannot continue without producing offspring. Therefore, the purpose of life is procreation.  Evolutionary theory tells us that while humans are complex mammals and have copious amounts of DNA, that DNA only exists within one person. In addition, while humans are finite beings, genes are immortal. The only way to spread one’s genetic information beyond themselves is through procreation. Genetic variation is a necessity in life, so the purpose of life is to procreate to pass on genetic material.  The tendency to procreate is natural since it is such an important part of life. Similarly, puberty is considered a life changing moment because of one’s ability to have children. Puberty and the natural human tendency to procreate occur because procreation is such a defining aspect of life. We owe our existence to procreation. We owe our future to procreation. Procreation is the purpose of life, as it is a defined feature of life.
The argument for procreation takes a very objective, evolutionary stance. Humans are not objective; we have bias, emotion, conflict, and differences. These aspects can supersede the need to procreate with other priorities which define their respective purpose of life. Several humans cannot or chose not to have children, but their lives still have purpose. For example, many members of the LGTBQ+ community do not have children biologically. In addition, many people who have changed the world did not have children including Leonardo da Vinci, Vincent van Gogh, Julius Caesar, and Socrates. The argument for procreation suggests that the lives of these people have no purpose or value since they did not have children. Of course, the previous notion is false.
Rejecting the premises