There's something wonderous about going out in the wilderness on a clear night and looking up at the sky. Devoid of the light pollution radiating from the cities and towns that many of us live in, we see a river of stars, a reminder that we are a small part of a large universe.
Per Occam's razor, the most realistic rationale for our existence and place in the universe is that we, and our universe, is part of some larger system. What that larger system consists of and what is happening in it that will affect our futures is outside our ability to know. Through scientific experiments, we have both theorized and determined that light has a speed limit, therefore as we are peering deeper into space we are actually seeing the light that was created in the past having only completed its journey into our eyes and sensors at this point in time. This means that as we look further into space, the younger the universe we are seeing. Stars get younger until we reach a point where there is a uniform light, seeming indicating a uniform field of energy, the background radiation, possibly coming from an high energy event, the big bang.
What lies further back in time, we don't have any clues into as this event clouds any light coming further. However, this doesn't mean that there is nothing before this event. Looking in our world, we see these high energy events happening all the time on a smaller scale. Events that cause immense heat and disassociation of the matter that happened to be in the proximity of the event. Events like sonoluminescence or the more common lightning strikes contain enough energy to break apart molecules and potentially form more complex ones as the temperatures cool. The simplest explanation is that we were simply in one of those events and are only now starting to form more complex structures as the universe cools.
In a similar note, we could explain the expansion of the universe along the same lines. In our everyday life, we encounter hundreds of chemical reactions which changes the density of the gasses involved. The expansion of the universe could simply indicate that we are in a reaction which is currently decreasing the density of the universe. Of course this would mean that we don't know if that will stay consistent or if that will one day reverse in direction.