Humanity
Jesus conquered sin and death by becoming human. It's in the Bible, Hebrews 2:14-15, NIV. "Since the children have flesh and blood, He too shared in their humanity so that by His death He might destroy 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."
By being fully human, Jesus made God known to us as never before. It's in the Bible, Philippians 2:5-7, NIV. "Your attitude should be the same as that of Christ Jesus: Who, being in very nature God, did not consider equality with God something to be grasped, but made Himself nothing, taking the very nature of a servant, being made in human likeness."
God presents the gospel through frail human beings. It's in the Bible, II Corinthians 4:7, NIV. "But we have this treasure in jars of clay to show that this all-surpassing power is from God and not from us."