"It was by surrendering to death the body which He had taken, as an offering and sacrifice free from every stain, that He forthwith abolished death for His human brethren by the offering of the equivalent...
"Naturally also, through this union of the immortal Son of God with our human nature, all men were clothed with incorruption in the promise of the resurrection. For the solidarity of mankind is such that, by virtue of the Word's indwelling in a single human body, the corruption which goes with death has lost its power over all.
"You know how it is when some great king enters a large city and dwells in one of its houses; because of his dwelling in that single house, the whole city is honored, and enemies and robbers cease to molest it. Even so is it with the King of all; He has come into our country and dwelt in one body amidst the many, and in consequence the designs of the enemy against mankind have been foiled and the corruption of death, which formerly held them in its power, has simply ceased to be....
"Thus by His own power He restored the whole nature of man.
"'For it became Him, for Whom are all things and through Whom are all things, in bringing many sons unto glory, to make the Author of their salvation perfect through suffering.' [Heb. 2:10] He means that the rescue of mankind from corruption was the proper part only of Him Who made them in the beginning. He points out also that the Word assumed a human body, expressly in order that He might offer it in sacrifice for other like bodies: 'Since then the children are sharers in flesh and blood, He also Himself assumed the same, in order that through death He might bring to nought Him that hath the power of death, that is to say, the Devil, and might rescue those who all their lives were enslaved by the fear of death.' [Heb. 2:14-15]
"By man death has gained its power over men; by the Word-made-Man death has been destroyed and life raised up anew."
My summary: The human race has fallen from the glory of its creation by God. Only the Creator of humanity can restore it, and in his love he comes to rescue us from corruption and death. He comes as a human, as one embodied person, and unites himself to human nature. Our corporate solidarity is such that his glorious presence within the human race reverses its corruption. The value of his sacrificial death is more than equivalent to the death which enshrouds the entire human race. We by faith unite ourselves to him in confidence of this Sacrifice and in the hope of the resurrection.
In taking on human nature Jesus restored the whole nature of humanity.