I am much more fluent in German than I am in Greek (I studied German for 10 years and Greek for only 3). If I learned one thing during that time, it's that an absolutely accurate translation from one language to another is virtually impossible. If that is true from one modern language to another, how much more difficult from the Greek of almost 2,000 years ago (NT) or even more (LXX) filtered through early 17th century English which is deceptively similar to modern but can trip you up . . . .
I would not trust to my own understanding even of the original Greek for my salvation. And those who do not read Greek are relying on various translators, commentators, and compilers of concordances.
That's why the Teaching Office is absolutely necessary. Otherwise you are putting your trust in anonymous committees of translators. Better the Early Church Fathers and their direct inheritors, who do not interpret everything anew but build on the foundation they were given.
Mary recognized that she needed the Savior. The Bible never says that Mary was anyone but an ordinary human whom God chose to use in an extraordinary way. Yes, Mary was a righteous woman and favored (graced) by God (Luke 1:27-28). At the same time, Mary was a sinful human being who needed Jesus Christ as her Savior, just like everyone else (Ecclesiastes 7:20; Romans 3:23; 6:23; 1 John 1:8).