Violation of one law of God kills, as well as violation of another law. The distinction between theirs and Adam's would be non-existent if they had died because of Adam's sin. People die because of their own sins. Adam was the father of the race as it fell under bondage to sin. However, the superiority doesn't exist in the number saved as opposed to the number lost.
Grace has more than enough power and adequacy to offset all that sin is able to do.
No matter how sin triumphed over men, grace had the antidote for it. It just takes one sin to condemn, and yet the benefits of Christ's death can justify one of many sins. Let us resist the temptation to downplay sin or certain sins. If all are sinners in Adam, then all must be saved in Christ. Calvinism is wrong when it claims that Jesus only died for the elect, that is, He only died for those God had predestined for salvation, apart of their own personal choices.