Life begins at the begetting. Note that this seed, the Word of God is said to be incorruptible. It is living and lasts forever. Note the emphasis on the fact that the seed, the Word, is incorruptible, hence there can be no hindrance of any kind to prevent the birth that is sure to follow. All people who are Spirit born have a new life, a new nature, the new man, the Spirit of Christ, the Spirit of God, and other names used in the Scriptures for such a condition.
Life begins with the begetting, with conception in the physical realm.
If not, then the Bible is wrong in these parallels. And, just as the physical begetting results in a birth, so does the spiritual. So we have the explanation of being born again. It is a resurrection from the dead. Nicodemus was to understand that he could not see or enter into the kingdom without a resurrection.