Was it part of God's plan for men to suffer and die?
God does not want men to suffer and die. God's original idea for man was paradise: life forever and peace between God and man and their environment, between man and woman.
Often we sense how life ought to be, how we ought to be, but in fact we do not live in peace with ourselves, act out of fear and uncontrolled emotions, and have lost the original harmony that man had with the world and ultimately with God. In Sacred Scripture the experience of this alienation is expressed in the story of the Fall. Because sin crept in, Adam and Eve had to leave paradise, in which they were in harmony with each other and with God. The toil of work, suffering, mortality, and the temptation of sin are signs of the loss of paradise.
(From Catholic Youth Catechism question 66)