There are always inherent dangers in applying metaphors to life, or even those conceptual structures that grow out of metaphors and the principle of sufficient reason.
Let us examine a Race. If you are a competitive person, I can understand how in your framework of Being, a race seems like an excellent metaphor for life. On the plus side, a race can be illustrative of how you excel, how you drive yourself, how you train. But then I could say "Life is Training for a Race" and it might work as well. The major difference is that you aren't beating any of your competitors. Not really, no, you can only prove you did by actually racing against them.
Racing against others usually requires everyone agree. We run around this track or course to get to a thin ribbon and leave everyone else behind. That sort of thing is easy to do in an actual race. It's what you're there for, but in larger life that sort of single-mindedness is virtually impossible because everyone is running in different directions.
A more evolved approach would be that you're running for your personal best, regardless of "who wins." This much I can accept until I start remembering other aspects of a race, not merely why I'm doing it.
Like a narrative, a race has a beginning a middle and an end. I was recently reminded of all of this in reading an essay on why it may be a good idea for us to drop the use of "narrative" in describing a life. (My only really big critique is that an actual definition of 'narrative,' even to explode it, appears to be missing.)
I hear you; I've read enough post-modern fiction and seen enough post-modern drama to know that Aristotelian formulas do not categorically apply. But remember those are deliberate attempts to subvert this notion that our lives are stories.
But life begins, as far as we know from our personal experience, rather mysteriously. Doubtless someone out there will reply that they remember everything since birth. How nice for you. I can't imagine the majority of us have such certainty. And Death is simply to quixotic to consider. If you believe in some afterlife where you can review everything in a PowerPoint debriefing, please let me know what you find. I only hope the box lunches are better than here when the plenary speaker is going over your accomplishments and failures. (Can I please have a crisp apple?)
That leads us to Myth. As a thoroughgoing Jungian I'm very aware of what the Archetypes from the Collective Unconscious are, but it does take a great deal of presumption to assert how they work. At most I would say they are hasty sketches that may explain important emotional events and how they remain powerful forces. The Collective Unconscious, and its interface with our manifold Personal Unconscious is simply beyond reliable reach in Existential terms, and frankly, I'm satisfied with being dissatisfied.
Perhaps I'm just one of those people who doesn't need a final answer, just as I don't need to finish a race. Myths give me insight because they are always psychologically true when they are occurring, just like myth's bed-mate: dream. But as with life, dreams and myth begin to change as I move through Time.
I am glad for Time though. It changes the track where I run for exercise with each circuit. It makes the books I love different with each reading. Time repaints paintings and it touches the snow of winter and cherry blossoms of spring with mutability. Even the gift of sorrow that comes with Time has its value.
So take it easy. Or run off the beaten track if you want to explore some other metaphors for living.