****(20) Therefore no one will be declared righteous in God’s sight by the works of the law; rather, through the law we become conscious of our sin.****
No one has ever claimed that Mary’s Immaculate Conception was accomplished by the works of the law.
The truth of the teaching of the Church is evident in that part of the statement which you have chosen NOT to highlight.
****by a singular grace and privilege of almighty God and by virtue of the merits of Jesus Christ, Savior of the human race, ****
Mary is indeed saved and preserved from sin by the same Grace by which we are all saved, through the same merits of Jesus the Christ by which we are all redeemed.
If you are going to try to use the CCC against the Church’s teachings, at least try to thoroughly read and understand it first.
Jesus is Mary’s Savior, just as He is for all who believe in Him.
Well then, why didn't God go ahead and do it for the whole rest of humanity, or at least all those of us who are saved, and save everyone a lot of grief?
If He did it for her, it certainly would have been within His power to do it for any one of us.