The Harrowing of Hell

Theologically, it is true that all humans would be destined to end up in hell were it not for the saving grace that flows from Jesus' death on the Cross.

This is the point of the legends about how Jesus broke down the gates of Hell and set the prisoners free.

Jesus' saving action is not confined by time limits. Just as He gave grace to Our Lady in her Immaculate Conception and to John the Baptist in his mother's womb before He was crucified, so He gave saving grace to many children of Abraham (Moses, Elijah, the prophets, the People of God) before He was born.

In the Transfiguration, Moses and Elijah appear in glory with Jesus.

God's hands are not tied by time. He can out outside of time in a way that confounds our linear thinking.