If any of you are familiar with quantum mechanics, one tenant is that until observed, things exists along a probability of all possible states. When we take a measurement or observe a particle, it's probability waveform collapses and we can determine with almost certainty either it's position or spin. This presents an interesting question: does the universe as we know it exist before we attempt to observe or measure it? This suggests that for the universe to exist as we observe it, we - the observers - are necessary. Otherwise the universe might exist in any state.
On the contrary. I don't think there is a grand purpose for life any more than there is purpose for rocks. Both simply came to exist due to circumstances. If we were to give ourselves a purpose, which we often do, I would say it's the pursuit of happiness and to achieve our ideals. I guess there are many interpretations of this purpose resulting in the world as it is. Sometimes people just try to survive and hope things will change for them if they can not change things for themselves. Other times people work hard toward these goals.