I've thought about this quite a bit. I teach religious education classes on Sunday mornings at my local church, 9th grade. And the kids will often have these same, deep questions about existence, purpose, and whether or not all of "this" is pure accident or design.
In my mind, looking at how large the universe is (or how large we, as humans, perceive it to be based on our limited ability to fully understand it), it simply amazes me that this solar system contains this planet. The perfect mixture of water, temperature, minerals, etc. No other planets that we know of have this precise and delicate balance to sustain life as we understand it. And on this planet, at some point life began. And developed, becoming more and more complex as time went on. And eventually, after billions of years, along comes the human race. An unlikely species to survive and flourish because at it's beginnings it did not have advanced technology. It lived in a world where it had to compete with other animals, and the only advantage it had was the ability to reason and think on a higher level (Why? Seems to go against how other animals evolve). Humans should have been wiped out very early on; not a favorable species to exist in the environment they existed in. But they were not. And then humans grew and developed, eventually becoming what we are today. Out of all the galaxies, all the stars, all the solar systems, all of the planets, here you and I are, living on this one, enjoying that precise mix of temperature, oxygen, water, atmosphere, and everything else that, as far as we know, does not exist anywhere else. At any point in time, something, anything could have been thrown off, completely derailing the evolution of this planet, it's species, and importantly you and I. Even the smallest change. But it didn't happen. And here we all are, not only living, but thinking and considering what our purpose is, or if we have one, searching for answers that go beyond science and trying to discover if there is any reason for spirituality, if there is an afterlife, if there is a supreme being (or entity, or governing force), and what it all means, if anything.
To me, the equation for which we, and our world, are the result is far too complicated and precise to have been left up to chance or some random occurrence. But that is my belief, I try not to push it on anyone or think poorly of them if they feel differently.