Future Wars

Imagine, if you thought you were a well adjusted man; a man who also happened to be a soldier. Now imagine that most of what you knew about yourself was a lie. In fact you believed several lies about your own life. What if you were involved in a war by other means? Future warfare was actually happening now, and you were right in the middle of it. Of all the modern equipment on the battlefield, you happen to be the most advanced war machine deployed.
You just don't know it yet. After the IED went off, Clay thought he was going to die right there in the road. When he woke up, he seemed to be in fine shape. They said he was not human. What does that mean?If he wasn't human, then what was he?