Why did we need to be saved?

Okay a lot of people seemed to miss the point in my last question, and answered a question that wasnt there? So to ask a new question, Why did we need Christ to die so that we could have forgiveness for our sins, considering that there was plenty of forgiveness/saving before him. How do you explain David being forgiven, Nebuchadnezzer, pretty much all of them, and the bible CLEARLY states that these people were forgiven, and SAVED. The whole nation of the Ninivites repented and were SAVED and god FORGAVE them. And fancy that Christ was not involved. And also you are saying that God is Powerless without CHRIST.