Everyone tries to be original. Every writer, every politician, everyone. But as history has shown countless times, there really is no original, though. There are only so many story arcs. There are only so many plots. There are only so many personality types and characters to choose from. There are only so many paper topics and angles at which you can look at something.
I have fallen into the trap of trying to be original, of trying to step away from cliches. But this is impossible. I found that the more I tried to step away from these things, the more I stepped into another cliche. I wanted to be original, and that in and of itself is unoriginal. As a Christian, I believe this more than ever, for it shows in Scripture. As the book of Ecclesiastes states over and over, "There is nothing new under the sun."
So, let's stop trying to be original and work with what we have. Though everything has already been written, it has never been written the way that you can write it. Just because there is no original thought does not mean that you need to simply give up on writing. Do not despair. Perhaps you can shed some light on a lesser-known thought. Perhaps you can write something brilliant with your ability to use the thoughts already known to man.
Only remember this. Do not merely do your writing for mankind, "for this is striving after the wind" (Ecclesiastes). But do your work for God alone. "Whether you eat or drink or whatever you do, do it all to the glory of God" (1 Corinthians 10:31). For when you do it for God's glory, you are fulfilling your true purpose which is "to glorify God and enjoy Him forever" (Westminster Shorter Catechism).