What are the main points in the prologue? As well as the departure?It was hard to understand. i am confused

In the early stages of the prologue, one becomes introduced to the idea that there is a universal sharing of experience and mythmaking, allowing different versions of the hero archetype; the hero with a 1000 faces.  It seems to me that Campell uses the prologue to establish this sense of universality.  If he cannot link different traditions together with universal application, then the premise of the monomyth is not as valid.  This monomyth is the similar structure that all heroic myths, regardless of culture and time, share.   With this in mind, Campbell uses the prologue to establish a perceptible pattern of different cultural expressions of the "sameness."  Some of the ideas he posits in favor of this position is his notion of tragedy and comedy, namely that the former is inescapable in all life and it is punctuated with moments of the latter.  He continues this line of logic with the notion of "the world navel," from whence all stories originate.  Campbell is trying to make the argument that there are some fundamental elements that all cultures in establishing their mythology share.  To better understand these elements allows for a more profound and deeper appreciation of the trials of the hero and the cultural expressions of mythology.