Here' are some Bible verses that describe our sinful nature:
Galatians 5:24
Now those who belong to Christ Jesus have crucified the flesh with its passions and desires.
Notice, this verse clearly implies that our "flesh" has sinful passions and desires that must be crucified through an act of our will to impose this crucifixion.
Galatians 5:19-21
Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality, idolatry, sorcery, enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions, envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God.
You'll notice that these actions are described as "deeds of the flesh". That means that they are innate tendencies of the flesh. The verse goes on to state that those who give into these tendencies and practice such things will not inherit the kingdom of God.
Ephesians 2:3
Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest.
Here we are told that we previously lived in the "lusts of our flesh" (or "desires of our flesh"), indulging in the desires of our "flesh" and of our unregenerate minds, and were therefore BY NATURE children of wrath.
Romans 13:14
But put on the Lord Jesus Christ, and make no provision for the flesh in regard to its lusts.
He are admonished to identify ourselves with Jesus Christ, choosing to live incarnationally as our Lord, and make no allowance for our flesh in regards to its desires. Yes, the flesh has innate desires all of its own.
Galatians 5:17
For the flesh sets its desire against the Spirit, and the Spirit against the flesh; for these are in opposition to one another, so that you may not do the things that you please.
Here we read of some ontological aspects of our humanity. We read how the flesh has desires that are contrary to the indwelling Spirit, and how the indwelling Spirit has desires that are against the flesh. Each having a contrary nature with contrary innate desires. It is because of this battle between two natures within us that we continue to struggle with being sinless.
Romans 8:5-9
For those who are according to the flesh set their minds on the things of the flesh, but those who are according to the Spirit, the things of the Spirit. For the mind set on the flesh is death, but the mind set on the Spirit is life and peace, because the mind set on the flesh is hostile toward God; for it does not subject itself to the law of God, for it is not even able to do so, and those who are in the flesh cannot please God. However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you But if anyone does not have the Spirit of Christ, he does not belong to Him.
Here is more human ontology. Here we read about how the mind that is set on the flesh (a mind set on pleasing the flesh and it's desires) is hostile towards God, and doesn't subject itself to God's will. In fact, it can't please God as long as it is determined to please the desires of the flesh. However, we are not in the flesh but in the Spirit. It is through the promptings of the Spirit that we deny the flesh and renew our minds through the study, meditation, and contemplation of the Word. This arms us in overcoming the flesh and it's desires when they arise.
Romans 7:5
For while we were in the flesh, the sinful passions, which were aroused by the Law, were at work in the members of our body to bear fruit for death.
This explains how the Law actually activates, or arouses, the desires and passions of the flesh. The moment the Law stipulates that we "shalt not" do something, there is the innate tendency in our flesh to fixate on what we can't do and desire it.
I illustrated this back when I taught Sunday school. I had my wife bake a plate of home made chocolate-chip and sugar cookies. Oh, they smelled so good and were so nice and warm. I put the plat on the table right in front of a group of 6 and 7 year olds. I had them look at it and smell it. Then I said, "But you can't have any. At least, not right now. We're going to go down to the Sunday school office and get some supplies. We'll be gone for about 10 minutes. No matter what, I don't want any of you to even touch these cookies." They answered, "Okay, Bro. Chris." We stepped outside the door and gave it a few seconds. We then peeked through the little window of the door and watched the kids. They were up and smelling the cookies. One kid even touched one with a finger. A little girl picked one up and began acting like she was going to eat it. Another child broke off a little piece of another cookie and ate it. Then the little girl who had a cookie in hand took a bite, and broke off pieces for other kids who were requesting a bite. A boy picked up another cookie and began breaking it up for himself and the other kids. They totally caved in and ate two cookies! Then they began to get concerned. You could see that they were scared and discussing what to do. We had to duck and cover because one child came to the door to see if we were in sight. After they closed the door, we returned to the little window. They were in the middle of re-arranging the cookies, trying to make it look like none were missing! LOL
Now, that little law demonstrated perfectly how the flesh is provoked. Here's the kicker, we had brought in cookies before and stepped away without saying a word. The kids eyed them, but didn't fixate on them, touch, or eat them. It was only after I gave them a law that their little brains fixated on the cookies, and the desire of their flesh was activated in full force.
It never fails. Tell a kid to calm down, or else someone is going to get hurt or kicked... 10 second later you hear the little sister say, "Ow! You kicked me!!!" If you tell them to not touch something, within record timing, they touch it. If you tell them to back away from the edge... they get as close as they can and peer over the side.
This rebellious impulse to do contrary to what is told to you is an innate part of our sinful nature. Law enforcement even has entire systems of investigation that takes this human trait into account when investigating the clues of a crime. By considering what is human nature to do when in various situations, they can uncover clues and recreate the scene of a crime quite well.