The point of the parable is the erroneous presumption that works is grace.
"He (the Pharisee) presumes to stand firm by his own works, and does not see that he and all men, even the true saints themselves with all their own righteousness and life, cannot stand before God; but are guilty of his wrath and condemnation, as David testifies in Ps., 130:3: "If thou, Jehovah, shouldest mark iniquities, O Lord, who could stand?" And Ps. 143:2: "Enter not into judgment with thy servant; for in thy sight no man living is righteous." Therefore he does not seek either grace or forgiveness of sins, nor does it occur to him that he stands in need of them..."
Certainly it seems more "humble" to say salvation is all of God and none of man (Salvation is of the Lord), than to assert, as you have done, that salvation is a "cooperative effort" between the Creator and the creature. Given your understanding, the accomplishment of salvation is made contingent upon and totally dependent on the willing accord of man who becomes the final arbiter of God's grace. God merely makes the offer; man accepts or rejects it.
"He only who is reduced to nothing in himself, and relies on the mercy of God is poor in spirit ("poor" translated from ptochos, which literally means "to crouch or cower as one helpless.") -- John Calvin
I'd be happy to discuss the Catholic teaching on cooperation with grace once we are done with the parable. I am the one reading the parable as written, and Calvin does violence to it with his mental contortions. Note that the pharisee thanks God for his condition. He does not presume anything about his works, nor does Christ indicate that his attitude about the tithing and fasting is the problem. The pharisee's presumption, very clearly expressed, is that he is not like the reprobates, and for that he is rebuked.