Who was the most important person in history?

Johannes Gutenberg, the inventor of the printing press. 
This man single-handedly made possible the preservation and mass-dissemination of
knowledge, which was previously all to frail.  Consider that before the printing press,
a person such as Aristotle might have amassed a treasure trove of knowledge, made
discoveries, contributed to society, philosophy, medicine, politics, and untold other
disciplines, only to be killed through the indifference of fate and the nasty, brutal,
and short nature of human existence.  Even if such a person had painstakingly written
their wisdom down, it would be far too easy for a tragic accident to destroy those
writings, to say nothing of the followers of a conflicting ideology purposefully scour
them from the face of the earth.  Gutenberg made it possible for knowledge to be very
nearly impossible to destroy.  Just my opinion.