He became

 ^"And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth." John 1:14

One of the biggest objections to the Christian faith is the doctrine of the incarnation. The belief that He(God) took on flesh in the form of a human being(Jesus) and submitted to the laws and limits of His creation. He stepped down from heaven and was separated from the Father. He came into this world as any other would, from a mother's womb. Even though His conception and  birth were indeed remarkable events, being conceived by the Holy Spirit, He still came to us in the same manner. So think about this: the Eternal, Almighty One True God, Lord of all creation, the great I AM, gave up everything to become the creation.

 ⁶ who(Jesus), though he was in the form of God, did not count equality with God a thing to be grasped, ⁷ but emptied himself, by taking the form of a servant, being born in the likeness of men. ⁸ And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. Philippians 2:6-8 ESV

  ^"For you know the grace of our Lord Jesus Christ, that though He was rich, yet for your sakes He became poor, that you through His poverty might become rich." 2 Cor. 8:9

 So He gave up everything to enter into the affairs of humanity. He came to redeem us from our fallen and sinful nature. We were created by God to love and worship Him, and to have a relationship. For us to freely love Him, the option to rebel needed to be there, which is what happened. He knew that we would go against His will and sin would spoil Paradise, and so He had a plan. His plan involved becoming the creature that needed saving. Why did He do this? While He  was on earth, He endured and suffered all sorts of afflictions and trials and faced temptations just like the rest of humanity and really was the Suffering Servant described in Isaiah:

 He is despised and rejected by men,
A Man of sorrows and acquainted with grief.
And we hid, as it were, our faces from Him;
He was despised, and we did not esteem Him.

⁴ Surely He has borne our griefs
And carried our sorrows;
Yet we esteemed Him stricken,
Smitten by God, and afflicted.
⁵ But He was wounded for our transgressions,
He was bruised for our iniquities;
The chastisement for our peace was upon Him,  Isaiah 53:3-5

The reason He became a man, the creation, comes to a head on the road to Calvary and when nailed to the cross where He faced and even carried with Him every single iniquity, and infirmity, and He became the very curse of this world, and took the burden and curse that the law commands where it says the one that hangs from a tree is cursed.(Gal. 2) Not only that, but in the Fall, part of the curse involving man stated that man would toil and reap thorns and thistles. Thorns were a natural symbol of the curse, and while Jesus was being tortured, he was mocked and given a crown of thorns. And finally He died, taking on the greatest part of the curse.
The curse of death that we deserve, Christ took on Himself, and then rose back to life to reign forever as our savior King. He became the creation, became the curse and died and came back from death to finally become KING.