"My point is that from the Catholic perspective, unless I misunderstand this difficult subject, there is no superhumanity because baptism removes the original sin."
Except that the doctrine of the I.C. also states that she was filled with every grace -- to such supercapacity that she was, from that moment, able to give away her extra grace to others.
I don't know about you, but I didn't get that at my baptism.
This is not a doctrine of the Immaculate Conception, but rather the doctrine of the Communion of Saints and the Mystical Body of Christ and how they interrelate. The saints have the same ability as Mary in this regard.
Regards
IC is not your ordinary baptism. So, by that fact alone she was made extraordinary.
This is what the Catechism says.
490. To become the mother of the Savior, Mary "was enriched by God with gifts appropriate to such a role". The angel Gabriel at the moment of the annunciation salutes her as "full of grace". In fact, in order for Mary to be able to give the free assent of her faith to the announcement of her vocation, it was necessary that she be wholly borne by God's grace. 491. Through the centuries the Church has become ever more aware that Mary, "full of grace" through God, was redeemed from the moment of her conception. That is what the dogma of the Immaculate Conception confesses, as Pope Pius IX proclaimed in 1844: "The most Blessed Virgin Mary was, from the first moment of her conception, by a singular grace and privilege of almighty God and by virtue of the merits of Jesus Christ, Savior of the human race, preserved immune from all stain of original sin." (Pius IX, Ineffabilis Deus, 1854.) 492. The "splendor of an entirely unique holiness" by which Mary is "enriched from the first instant of her conception" comes wholly from Christ: she is "redeemed, in a more exalted fashion, by reason of the merits of her Son." The Father blessed Mary more than any other created person "in Christ with every spiritual blessing in the heavenly places" and chose her "in Christ before the foundation of the world, to be holy and blameless before him in love." 493. The Fathers of the Eastern tradition call the Mother of God "the All-Holy" (Panagia) and celebrate her as "free from any stain of sin, as though fashioned by the Holy Spirit and formed as a new creature". By the grace of God Mary remained free of every personal sin her whole life long.
We see two things: she was redeemed and she was freed from original sin. This is to say, she became a saint and was baptized at conception. I did not become saint yet, so there is a difference; but as example of many saints show, hers is not a superhuman condition.