Long before Noah's time there were already craftsmen in bronze and iron. In shipbuilding metal would have been stronger than wood, yet God wanted the Ark to be built of wood. There is a good reason for it.
Wood comes from trees.
Several Bible verses describe our Lord Jesus Christ was crucified by hanging on a tree . When we talk about the Ark that was constructed of wood that saved lives our minds should also be thinking of the Cross that our Savior was crucified that saved us.