DOES HUMAN NATURE VANISH AS SOON AS WE ARE BORN AGAIN?

I have watched professing Christians and have determined that for many there is a misunderstanding of what human nature is. Human nature is, according to the dictionary: the qualities common to humanity; the unique elements that form a basic part of human life and distinguish it from other animal life. It is the makeup all humans everywhere and at every time in history share. It does not change. A quick overview of world history tells us that. The pursuit of happiness is a priority, but first and foremost is what we call instinct – self-preservation, and second is procreation of the species. We all have a natural “ego” which resists alteration of our “characteristics” that make us “individuals” in this great big world. That is why some people consider themselves a model for all humanity and try to make others conform to their own likeness mentally, spiritually, even emotionally.

Since “human nature” includes all humans, when we look at this subject and really think about the topic, we are forced to realize that the answer to the question posed is obviously, “no!”

Equally obvious is the fact that the Bible tells us there will always be a war raging within true believers, a fact addressed most notably by the apostle, Paul. He describes it this way in Romans 7:14 (CJB): For we know that the Torah is of the Spirit; but as for me, I am bound to the old nature, sold to sin as a slave. 
15 I don't understand my own behavior - I don't do what I want to do; instead, I do the very thing I hate! 
16 Now if I am doing what I don't want to do, I am agreeing that the Torah is good. 
17 But now it is no longer "the real me" doing it, but the sin housed inside me. 
18 For I know that there is nothing good housed inside me - that is, inside my old nature. I can want what is good, but I can't do it! 
19 For I don't do the good I want; instead, the evil that I don't want is what I do! 
20 But if I am doing what "the real me" doesn't want, it is no longer "the real me" doing it but the sin housed inside me. 
21 So I find it to be the rule, a kind of perverse "torah," that although I want to do what is good, evil is right there with me! 
22 For in my inner self I completely agree with God's Torah; 
23 but in my various parts, I see a different "torah," one that battles with the Torah in my mind and makes me a prisoner of sin's "torah," which is operating in my various parts. 
24 What a miserable creature I am! Who will rescue me from this body bound for death?

If it was this difficult for an apostle, the great apostle Paul, what makes us think we should expect an easier time?

I was raised in church but always felt like I was missing something. Now the Word of God excites me! My curiosity enhances the pursuance of discernment. I have often felt discouraged, but not totally defeated knowing that in all these things we overwhelmingly conquer through Him who loved us.