Was any human person ever preserved from original sin?
Yes, the Blessed Virgin Mary was preserved from original sin from the moment of her conception in view of the merits of Jesus Christ. This privilege is called the Immaculate Conception.
First, we have God overlooking the history of man, from creation to apocalypse. For us, time is linear. For Him, there is no time, so He sees everything in history—past, present, and future—all at once.
Next we see God looking down on the sacrifice on the cross for the redemption of the entire human race. It was on the cross that He redeemed us and brought sanctifying grace in the world—the sort of grace everyone must have to be holy and attain heaven—even Mary.
In a manner of speaking, the Father reached down to His Son and took the sanctifying grace the Son won for us with His sacrifice and…
applied it to the soul of the Blessed Virgin Mary at the moment of her natural conception in her mother’s womb. This is how Jesus was given a perfectly clean vessel to grow as He came into the world. This is the Immaculate Conception.