What you fail to understand is that Mary was the mother of Jesus the Son of God on this earth. This is extremely simple to understand.
If, in His superior wisdom and knowledge, God wanted us to view Jesus as God, and not the Son of God don't you think He would have made that abundantly clear in Scripture?
Oh, I forgot the RCC teaches God's word is incomplete and insufficient to lead people to His truth. After all, Christianity was a growing faith for hundreds of years before the RCC started mandating doctrines and dogmas, so that part of history is wrong, right?