Trying to understand God's forgiveness

Numbers 14
As I read this I am seeing something that I don't understand.

The twelve spies have come back and ten of them have discouraged the people. Quite the rebellion ensues; a mutiny, falling short of an action plan. And then there is talk of stoning the leadership. No less than murder.

Verse 11 has God responding by saying, “how long will they treat me with contempt?”

Moses intercedes on their behalf (not that they deserved it.)

Look at verse 20. In response to Moses' request God says, “I have forgiven them, as you have asked. Nevertheless – not one of these who saw my glory will enter the promised land.”

Now look at 2Samuel 12:13
David has committed adultery with Bathsheba, had her husband murdered, and now there is a child resulting from his sin. David chooses not to look at what he has done and therefore God sends Nathan the prophet. David responds to Nathan with, “I have sinned against the Lord.” Nathan's response, “the Lord has taken away your sin..., but because you have.... the son born to you will die.”

Questions:
1. Without the shedding of blood there is no forgiveness of sins.
1a.)In either case, Israel's or David's, where did this take place? We do not see it.
The shedding of blood has to go back all the way to Adam. There is a logical path in that, and it becomes visible when you choose to follow the path through Abel and his brother Cain. The teaching did not die that day and I believe that Israel was aware of it.
You can see God brought this back to Israel through Moses, and that Moses made it clear that the shedding of blood had to take place for the forgiveness of sins.
This of course, is our life, for Christ's blood was shed for us.
Assumptions:
A. That Moses' intervention and God's response were all immediate.
B. David must have offered a sacrifice for the sins he had committed.

Considerations:
a.) No cell phones, so for the mutiny to escalate through over a million people time has to pass. God's punishment was upon the entire congregation. Why would he punish those not guilty? That would imply that they all conspired, not just a handful. There is nothing to make us believe that anyone repented of theirs sins through sacrifice.
b.) Although David may have sacrificed what destroys that theory is that Nathan had to be sent by God. And, until confronted, David had kept this all a big secret, therefore, no admission of guilt. Confronted and caught, David makes his declaration, “I have sinned against the Lord.”

In either case, with my physical eye, I see people coming against people; God sees it differently. David made a truthful statement and yet odd, in that he had sinned against several people in order to get what he wanted, and he made no mention of that. Perhaps what was important was what the biblical writers, led by the Holy Spirit, placed upon the page for us to see, that David had sinned against God. In Numbers, while the mutiny against Moses is unfolding, God tells Moses that the people have sinned against God.
If you consider that scripture tells us that we are in Christ, then sins committed against us, are committed against Christ, and ultimately against the Father as well. Israel nor David had the relationship with the Father that we have, and yet God took any actions performed against those He considers his, to be actions against him.

We have a relationship that we do not fully comprehend, with a God that we can only understand through the Spirit. Having his life in us by accepting our adoption through Christ, puts that Spirit within. As loving as we want to perceive God to be, he is the last person that you want against you, as we go on the rampage against those who belong to him. And here is the worst part. It is difficult to tell who it is that belongs to him, because not all of us have managed to stay out of the mud puddles that life has put in our path, and some do not have the money to buy the right clothes that make us appear holy.
I have been taken back as people that I never expected to have a relationship or understanding of God, have made some rather bold, unexpected statements. They have in those moments demonstrated a boldness that I desire, as my fleeting self-righteousness gets blown out the window.