Jesus did not “die for our sins.”
He died so that humanity could be judged honestly according to its merits.
In other words: God the Son was presented with both the best humanity had to offer — His disciples, and those, too, seem pretty dull — and the worst — His murderers.
Jesus came so that given these two extremes, He might in His own heart and guided by own personal experience judge whether the virtues and strengths of the totality of humanity outweighed its vices and faults.
It so happened that we all have been judged on the whole greater than zero, an asset and not a liability.
The way Christ’s decision benefited us is that the souls of those who had died before the Incarnation were awakened and brought into either a temporary afterlife of natural happiness or into full glory, and similar fate awaits now everyone else.
It is on this contingent event — meaning that it did not have to happen — that the Christian religion is built. Jesus was graced first with knowledge of the created universe, then with full power of the Father, and lastly with charity toward humans. His freely given acceptance of that final grace despite the injustice done to Him and the suffering He experienced was a crucial component of the entire divine project.