The two most prominent viewpoints of the origin of man is evolution and creation. Now, you don't need a rocket scientist to figure out that I am not a fan of evolution. It is a silly theory that has too many holes to hold any water (edit March 4, 2016: not that I would completely out-rule a theistic evolution, but so far the evidence seems to point against this as well). I say this because I have done research into evolution in the past and if prompted I can list a number or reasons why evolution can't have been the way man originated. That being said, we must have been created by God. From this fact comes the obligation to figure out why God created us. Was he bored? Did he want entertainment? The clues that gives us answer to the question of why God created us comes from the world views about God. There are different pieces of literature that claim to know God's intent in making us, but out of them, the only trustworthy one is the Word of God itself, which exists in the Holy Bible. In this book God lets us know why we were created.
26Then God said, “Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.”
27So God created mankind in his own image, in the image of God he created them; male and female he created them.
So not only were we created to take care of the creatures of this earth, but we were also created in the image of God. That means, first and foremost, we need to reflect the image of God. If we don't do that, then we have deviated from what we were created as. God created us in the image of God for a reason, not just so we could have a decent starting point, but so that we could have the perfect existing point.
What does it mean to be made in the image of God? It could mean many things, but I think it is best summarized with an illustration. What reflects our own image as humans? Mirrors. If for some reason the mirrors reflected back an inaccurate picture of ourselves, it wouldn't be functioning properly. That being said, those who don't reflect the glory of God by being his image-bearers have deviated from their purpose of existing. Indeed, at the sole of the purpose of our existence is to glorify God, as doing so reflects the image in which we were made.
How do we best reflect the image of God? By getting to know Him, of course. In order to show how awesome someone is one can't just make up a bunch of lies, one has to actually know the truth in order to brag about someone. The same goes for God. We can get to know God by talking with him, and listening to what he says to us through the scriptures, through the Bible. Of course the more we get to know God - the more we fill ourselves with knowledge of him - the more we end up doing what he commands, actively reflecting his glory to others through our obedience.