Lucy, this ‘splained it purty well to me...
Romans 5:12-21
12 Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men[a] because all sinned— 13 for sin indeed was in the world before the law was given, but sin is not counted where there is no law. 14 Yet death reigned from Adam to Moses, even over those whose sinning was not like the transgression of Adam, who was a type of the one who was to come.
15 But the free gift is not like the trespass. For if many died through one man’s trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many. 16 And the free gift is not like the result of that one man’s sin. For the judgment following one trespass brought condemnation, but the free gift following many trespasses brought justification. 17 For if, because of one man’s trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ.
18 Therefore, as one trespass[b] led to condemnation for all men, so one act of righteousness[c] leads to justification and life for all men. 19 For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous. 20 Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, 21 so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord.
Eve relates to the sin of Adam differently than everyone else.
in post 451, Ealgeone rightly notes that Christ is excluded—even though he is not specifically mentioned as excluded.
Duns Scotus solution was that original sin would have naturally extended to Our Lady as well had not the grace of Christ sanctified her at the instant of Her conception, thus saving her in a particularly powerful way, and making Him her savior in a more fundamental way than anyone else.
So yes, the sin of Adam extends death to or towards Our Lady, but at the moment it would have impacted her, she was saved by Our Lord.
I’m sure it may be explained better and more precisely, but that is at least the general ball park of Duns Scotus solution.