In this transaction one becomes a son, or child, of God which, in analogy with natural birth, would indicate that a new life comes into existence. All of this brings some questions. If only the reborn being is immortal, then the unregenerate life must cease to exist. If the unregenerate life is annihilated at baptism, then it endures no punishment. If we accept the premise that a new life is created in the new birth, we must conclude that only the reborn person who becomes apostate is subject to punishment.
Metaphors are only one of the many literary devices used in scripture.
A metaphor is a figure of speech where a word literally denoting one idea is used in place of another to suggest likeness or analogy between them, like Jesus saying he was a door' a vine, or a shepherd. So, an abrupt, sanctifying change of life is referred to as a new birth. The change initiated by faith which produces repentance confirmed by baptism is like a person putting off one life and putting on another. An old identity is repudiated and a new one is established with Christ involving new desires, aims, goals, and purposes. The physical body is not changed in this conversion process.