Partially true, but one must point out that everyone you mentioned also had what they saw as a complete set of rights and wrongs. That it is different from your set or my set doesn't change the fact that they had things they saw as wrong and things they saw as right.
But I would also point out that even Jesus Himself saw the world in something of a gray. When He first came across Mary Magdelene, she was a prostitute. And she was about to be stoned by the crowds for being one, as the law that God handed down had said to do.
That is when Jesus said that "he who is without sin cast the first stone." This convinced them to leave, but in this case Jesus did convince many to go against the law of God Himself. Did Jesus sin because of this?
No. He was following the spirit of the law, which was to bring and keep all close to God so that they would follow Him and benefit by such. The crowd was following the letter of the law, but misunderstood its spirit and reason. Jesus saw that spirit and reason, and went against the law as it was written to uphold what it was about.
The situation was a gray area, Jesus found the way to a clearer right in it.
So there can be clear differences in right and wrong, but in many cases the situation can be a gray area.