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?