Is there an ontological change in human nature after Jesus Passion and resurrection? I came across this passage from Jacques Servais, commenting on Thomas Aquinas’ view on Christ’s Passion: 


  God himself acts in human nature by regenerating it from within. He, in fact, wanted, to save us, not through his will alone, but through the meritorious and atoning work of the Cross.


See the original here

I was wondering if that means that after the fall of Adam, humanity as it was desired by God was degraded, ontologically speaking. 
When Jesus came and delivered us from sin, He, being sinless and divine, has restored our nature, therefore establishing an ontological change.
Human nature cannot be entirely destroyed by sin, and, as St. Thomas Aquinas writes in Summa Theologica III q. 89 a. 3, man can be restored to his former dignity by penance or even to a lesser, equal, or greater degree of virtue.