Lol. Believing in a human "nature" such as the one you've just concocted makes it clear the RCC knows nothing about who men really are.
Self-deception is so unattractive.
As Katherine Hepburn said to Humphrey Bogart on the African Queen -- "Nature, Mr. Allnut, is what we are put on this earth to overcome."
IMHO this leads to a kind of seam in theology: God made all things good. Human nature is ab origine good. What we SEE empirically is corrupted human nature -- excessive here, deficient there, and perverted over there.
When they speak of "human nature" they are speaking of this empirical thing. When we speak of it we look at the implied excellences and speak of them, and then say that, in a way, the humans we encounter fail to live in accordance with their nature, and that that is one way of describing sin.
While they appear to have Occam playing on their side, they implicitly give up the excellence of creation OR end up losing the illusory simplicity of the seemingly empirical derivation of their ideas of human nature.
What a nugget!! How do you come up with these?
And, of course, as you say to believe in a human nature that is free to act (and be provident for ourselves) is utter nonsense. But, it may explain why the RCC view tends to elevate men and leads to the Nebuchadnezzar view ("I will make myself as the most high"). Hmmm.
Perhaps you could explain why or how it was that each of the preceding covenants (the Covenant of Adam, the Covenant of Noah, the Covenant of Moses, etc.) were broken by the freely exercised will of man and how that precedent no longer applies to the New and Everlasting Covenant established at the Resurrection?