Understand that mans free will lives in the flesh that is corrupted.
Understand you are wrong on this. The will is a function of the soul, not the flesh. Our bodies have no capacity to make choices. They work autonomously. You do not choose to make your heart beat or your digestive system to function.
The sin nature (law of sin) that is in the flesh works similar to instinct in an animal. The difference lies in it's leading direction. Where instinct in an animal pushes it to be the animal it is, (ie. the instincts of a dog make it behave like a dog), the law of sin in our flesh push us to be not human (ie. to behave as not made in the image and likeness of God as exemplified in the life of Christ). When that is coupled with our ignorance of God (spiritual death), it becomes a recipe for the death of our humanity.
Christ says if you want to be great in the Kingdom of God you must be the servant of all. The sin nature says if you want to be great you must serve self first, forget the rest.
It is that self-serving instinct that is the sin nature at work in our flesh that ultimately we have no control over that deceives our thinking which is easy to do because we lack the knowledge of the truth of God.
This is why salvation is by grace and freedom comes through Christ who is the Truth. When the ignorance of our thinking is replaced with the truth of God and we live by grace in the power of the Holy Spirit, we are made free to be truly human in all it's perfect God given intent.
You can quote John 1:13 all day long but the reality is you have no idea what it means. The soul is not born corrupted because it is created by God, therefore the will is not corrupted. It is however bound by the sin nature at work in the body and therefore not free at all except for the Lord's intervention which He always does from the moment a soul can think. Then and only then (without grace) would the soul become completely depraved and beyond redemption. That would include one's thinking, emotions and will.
The "will of the flesh" has nothing to do with having the body make choices. It has to do with physical impulse or physical desire. What we would call today in some instances, chemistry, other instances, lust which the mind then follows under the body's impulses. The choice (will) remains in the mind, not the body.