For anything that was ever made or manufactured there is a purpose for it. God who is our Creator have the respective purposes which He created all of us. But it is quite disheartening that some people move around the earth without having knowledge of this. Man is too important for God to just simply create without a purpose.
The moment we realize the purpose for our existence our lives take a different turn. An invention is not useful until it begins to fulfill the purpose for which it was invented in the first place. An invention does not do what it wants to do but does what the creator wants it to do. In this case we are the invention and God is the Creator. God has a purpose for which He created us.
John 14:12 - Verily, verily, I say unto you, He that believeth on me, the works that I do shall he do also; and greater works than these shall he do; because I go unto my Father.
We are called to do great works. We are not mere inhabitants that walk across the earth. We are a lot more than that. God has entrusted each and every one of us to be doers of good works. God is pleased when we live ourselves in total commitment to the fulfillment of the purpose for which God created us.