Experience is the basis of understanding, but imagination is what gives context and meaning to our experiences.
Two people can experience the exact same event, but perceive it in two different ways. Even the most ardent of atheist scientists will disagree on the meaning of an experience they might share. And, since it is our perception of experiences (not facts) that guides our behavior, the difference is everything.
During the short period that we humans have been conscious on this planet reality has not changed, but our perception of reality has gone through slow, steady changes and major upheavals. These changes affect the choices we make, which, in turn, influence the way we live, the impact we have, our individual growth, and our overall evolution.
From this point forward, the evolution of our perspective cannot be left to the whims of random chance.