While Mary is most likely not in the mind of the author of Hebrews as he writes this passage, it is certainly not a verse which Catholics would like to place anywhere near Marian doctrine. Jesus is not great because of His earthly lineage or anything they did. He is great because He is God. Period.
As for Dave's question in regards to how Christ could save fallen humanity without becoming fallen humanity, the Catholics have their own quandary here. If Jesus was born to an immaculate Mary, and was thus without the stain of original sin, was He really part of fallen humanity?
I thought it would be malakhi who would ask this. Glad to see you around again.
As you may be aware, I was somewhat imprecise in my wording. Jesus does indeed need to be of the same lineage, to be related to the existing line of humanity in order to redeem it. As I have said, if He is cut anew from some fresh strain, then He is not of the line of David and fails to fulfill prophecy as well.
Catholic concept of Original Sin is of a lack, a depravity. What is lacking in the one with this "sin" is a relationship with God.
Jesus, being God, could in no way be said to have "Original Sin." How could God lack a relationship with God.
(And BTW, Mary's Immaculate status is not relevant. Jesus does not inherit his lack of Original Sin from Mary, but because of who He is.)
SD