5 ways of Aquinas

St. Thomas Aquinas developed 5 ways in which he believed entirely prove the existence of God. His argument appear to be incredibly sound and cannot be disproved but he makes some faulty assumptions and without them his arguments wouldn't make nearly as much sense. He assumes that God is the unmoved mover. How does he know that God is unmoved. What if there was a mover before god. HIs 5 ways don't answer the question of how God became himself in the first place. Because Aquinas makes it appear that God basically placed himself there. So he didn't exist yet he made himself exist. That neither makes sense nor is it rational. He says then that God is the uncaused first cause but how is that possible. If he proceeds to say that nothing can be the cause of itself. Then lines down he says therefore their must be an uncaused first cause (GOD). So what makes God the exception to the rule. Aquinas' message is clear but not valid. He makes some enormous assumptions that he is in no place to make. He doesn't know God so how can he assume that he is and unmoved mover.