1 Corinthians 15:21

'For since by man came death, by man came also the resurrection of the dead.'

This was why Jesus had to come as man. By man, and his sin, death came into the world. It was therefore necessary that another Man should come Who would defeat sin and death, provide the ransom, and demonstrate it by rising from the dead, thus making resurrection from the dead a certainty for all who are God's.