Why just the mediator be a true and righteous human?
Romans 5:12 – Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all people, because all sinned
Romans 5:15 – But the gift is not like the trespass. For if the many died by the trespass of the one man, how much more did God’s grace and the gift that came by the grace of the one man, Jesus Christ, overflow to the many!
1 Corinthians 15:21 – For since death came through a man, the resurrection of the dead comes also through a man.
Hebrews 2:14-16 – Since the children have flesh and blood, he too shared in their humanity so that by his death he might break the power of him who holds the power of death—that is, the devil— and free those who all their lives were held in slavery by their fear of death. For surely it is not angels he helps, but Abraham’s descendants.
Hebrews 7:26-27 – Such a high priest truly meets our need—one who is holy, blameless, pure, set apart from sinners, exalted above the heavens. Unlike the other high priests, he does not need to offer sacrifices day after day, first for his own sins, and then for the sins of the people. He sacrificed for their sins once for all when he offered himself.
1 Peter 3:18 – For Christ also suffered once for sins, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive in the Spirit.