That's a pun referring to his flesh.
This is now bone of my bones And flesh of my flesh; She shall be called Woman, Because she was taken out of Man.”
Genesis 2:23
Ha, love your humor lol. I was going to post that verse as a reply but you beat me to it lol.
How did Adam’s sin, (disobedience) spread to all mankind, if not through procreation of the human race?
You see, I don't look at it that way.
Adam's sin did not spread to all mankind. What spread to mankind was the result of his sin. Death was the result of his sin, and death spread through all humanity because of that sin. Think cause and effect. If i knock this domino down, it will set off a series of events. I also want to note that not only did death enter the earth through Adam's sin, but the ground was also cursed. There is much we could write on this matter, but I don't want to stray to far from the point.
How is it all mankind has a body that contains sin, (sin nature) if we didn’t inherit from our parents going back to Adam?
We are born into a sinful world. Sin surrounds us and it can leave an imprint within us. Science has actually found that if a parent experiences a traumatic event, that event can leave an imprint within our DNA which can be passed down through conception to a child. We don't inherit the sin, what we inherit is our parents' past and present environment which is full of sin. If sin is considered 'normal', within the home, then this sin is passed down to each generation until that cycle is broken. We call this generational sin which is a culmination of imprints of past and present environments. It's cause and effect. As a result, we have the choice to either choose life, or choose death. We can break generational sin and through Christ, we can be set free.
Do you understand that our flesh contains sin that desires to gratify its lustful cravings?
Yes, I do understand that. But that in and of itself is not sin. What you're refering to is what lured Eve into sin. James puts it this way.
NIV James 1:14 but each person is tempted when they are dragged away by their own evil desire and enticed. 15 Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.
That desire has to be conceived.
Many don't understand this. So I will just say it.
We are NOT held accountable to God for every thought that pops into our head, regardless of how sinful that thought may be. What we ARE responsible for is what we do with that thought.
As an example. let's use gluttony as an example. Your obese and the dr says that you have to loose some weight or you're going to die. Out of nowhere, you get this thought to each a chocolate cream pie, and your urges are strong. You didn't solicit this thought and it just came out of nowhere. Is this sin? No, because it has not been concieved. For this thought to conceive, you have to entertain it, mediate on it, visualize it. In other words, you have to bring life to this sinful thought by giving it space in your mind that you actually want to each the chocolate cream pie. and once you give it life, it's conceived and you're one step closer to actually going through with it which leads you to death.
It goes back to that struggle we all wrestle with. Call it two souls or whatever you want, but there are two forces in our life and they wrestle.