Apparently, Isaiah 53 says nothing about incarnation. However, the first part of verse 2 says, "For He grew up like a tender plant before Him, / And like a root out of dry ground." In the New Testament economy, it was unveiled and reported concerning Christ that He was like a tender plant, like a root out of dry ground. This certainly is a reference to Christ's incarnation. Just these few words indicate that Christ is the incarnated One. As such a One, He grew up before God like a tender plant.
The second part of verse 2 says, "He has no attracting form nor majesty that we should look upon Him, / Nor beautiful appearance that we should desire Him." Very few people would pay any particular attention to a tender plant. In one sense, the Lord Jesus is beautiful. There are a number of hymns in our hymnal concerning His beauty (Hymns, #170-178). However, in another sense, Jesus is not beautiful. He has no beautiful appearance that we should desire Him.
Verse 3 says, "He was despised and forsaken of men, / A man of sorrows and acquainted with grief; / And like one from whom men hide their faces, / He was despised; and we did not esteem Him." According to the account in the four Gospels, the Lord Jesus was continually despised, was forsaken of men, and was a man of sorrows who knew nothing but grief. Furthermore, He was like one from whom men hide their faces. Men did not like to see Him, and they did not esteem or regard Him (Matt. 13:54-57). Based on this account we would not consider such a One as a great man, nor would we consider ourselves inferior to such a One.
Second, in the report of the prophets and the revelation of Jehovah, Christ was revealed as the crucified Redeemer. As our Redeemer, Christ sacrificed Himself for our trespasses, or, for our sin, for the accomplishing of Jehovah's eternal redemption (Isa. 53:4-10a). It is difficult to understand how one who is great could be crucified. Those who are crucified are usually very low and mean. Nevertheless, our Redeemer was crucified, sacrificing Himself for our trespasses for the accomplishing of God's eternal redemption. All these things concerning Christ are revealed in a heavenly language. Today we call this the gospel, the glad tidings, the good news. Actually, however, according to our natural human thought, we might wonder how such words could be considered as glad tidings.
When they go out to tell people about Jesus, many Christians do not speak of Jesus in this way. They dare not tell people that Jesus was a tender plant, that He was like a root out of dry ground, and that He has no beauty, attracting form, or majesty. Perhaps you have never told people that your Jesus was like a tender plant growing up before God and that He was like a root out of dry ground, growing with difficulty because there was no water. We prefer to know Christ and to present Christ as a great person in the Old Testament economy. Thus, we need the Lord's grace to bring us into the New Testament economy.