At Creation, our first parents were given an extra gift of immortality. When they sinned, separating themselves from God, they lost that gift, and the soul and body became subject to that separation we call death. Because we were originally made to be free of death in Eden, we long to return there. If we suppress that longing for unending life, we will stop seeking it.
“If God is with us, nothing can come against us—not even death itself.”
God did not will, but only permitted death. In the Incarnation of his beloved Son Jesus, he suffers the very death we brought on ourselves in order to free us from the very root and cause of it: our sin. By his death, the possibility of immortality is regained, if we seek it from him.