It is not a fair assumption to at least admit to the possibiblity. We are ignorant beings, in spite of all the knowledge we have gained throughout the years. We may merely be subcreations of another form of life. It is true that we know much, but in comparison to the span of life as we know it, we know very little. The belief that extraterrestrials exist is a truly controversial one.
Skeptics have every right to doubt the idea.
The important thing one must remember is the significance of the openness of mind. Any findings to support the notions of UFO's could lead the human race to an infinite number of answers to some of our greatest unsolved myths, including that of crop circles. There is a long stretch to go before we will find indoubitable answers to our questions. Again, another question to which we may never find the answers to. We can only rely on the information we are given from the findings of science and our personal beliefs, intuition, and depthness of thought.