That's not the point. The ransom analogy suggests that X pays something to Y in order to release Z from the power of Y. If you say Y = Z, the analogy is ruined.
The "analogy" is wrong. Christ (X) owes nothing to Satan (Y) that He should purchase man (Z) from the power of Satan (Y) by means of a transaction between he and Himself. Satan never owned us in order to sell us and I (Z) am not Satan (Y) as you claim by your Y=Z analogy. Your analogy was ruined from the start because you cannot "calculate" the truths of God.
Satan temporarily has power over us who are not God's children, but he does not have ownership that God should purchase man from him. He died to purchase man from the power of Satan, of darkness, of sin. Jesus died and rose again to life to take away the great divide between man and God so we might have communion with Him. You cannot take what Jesus Christ did for you and put it into a mathematical formula.
"To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me."
" Giving thanks unto the Father, which hath made us meet to be partakers of the inheritance of the saints in light: Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son: In whom we have redemption through his blood, even the forgiveness of sins:"