As per the understanding below, how was the human nature injured by the Holy Spirit in the Garden of Eden, and how did that injury conduce to charity?
Adam and Even essentially traded innocence for wisdom. Without wisdom, the natural happiness afforded to them in the Garden was sufficient and fitting for them. But it was small happiness. I restate my opinion that in the Garden, Adam and Eve were "little more than zombies."
Upon obtaining wisdom, humans became insatiable in their desires. We no longer want just the amenities of the Garden. We want everything -- let's borrow a clue from St. Thomas and call it the "sole contemplation of God seen in His essence," such that "the blessed... see Him, and in seeing Him, possess Him as present, having the power to see Him always; and possessing Him, they enjoy Him as the ultimate fulfillment of desire."
Upon the concomitant loss of innocence and withdrawal of divine favor, we also came to suffer a great deal. We feel sorrow and pain that demand to be alleviated.
Thus, we now both suffer positively and are deprived of pleasure negatively. These provide the materials for interpersonal charity which is our willing good to each other: Smith could succor Jones either by relieving his suffering or by providing pleasure.