It's rather hard to argue with, "All have sinned and fallen short..."
Of course. That's Who made her sinless and immaculately conceived.
And that is your non-scriptural interpretation.
From other scripture, if not from common sense we know that Jesus was without sin and did not fall short. Yet that verse if taken literally would contradict that. Further, Noah, for example, is mentioned in the scripture as man perfect in every way, and Mary is described as full of grace. We conclude that the intention of St. Paul in Romans was to describe the overwhelmingly true sad condition of man, while allowing for implied exceptions.
Christ is most definitely Mary’s Savior, and given her fullness of grace before the Annunciation, I don’t see what other conclusion one can reach but that Christ made her sinless and immaculately conceived.