LUKE 2:52 And Jesus increased in wisdom and in stature, and in favor with God and man.
S'plain this.
Jesus was at the same time fully God and Fully man. These two natures are not "mixed together," (Eutychianism) and are they combined into some kind of God-man nature (Monophysitism). They are separate yet act as a unit in the one person of Jesus. This is called the Hypostatic Union.
God’s favor is shown by grace, and though Christ had the benefit of infinite grace from the beginning of the Incarnation, he was still fully human, with all of the human limitations. For Him to suffer He had to have the ability to feel fear and pain. As man he would need to acquired knowledge by experience, as all humans must.
C.S. Lewis argued that one of the ways that Jesus "emptied Himself" was of omniscience, and that His human nature couldn't be both fully human and omniscient since the brain has a physical limit to its capacity.