Y'shayahu / Isaiah 42 clearly tells us that the Jewish people are G-d's servant -- a servant who is often blind and deaf to G-d's message, but as infuriating to G-d as is His servant, He will never desert the Jewish people.
Y'shayahu / Isaiah 41:8 - 9. "But you, Israel My servant, Jacob whom I have chosen, the seed of Abraham, who loved Me, Whom I grasped from the ends of the earth, and from its nobles I called you, and I said to you, "You are My servant"; I chose you and I did not despise you."
"For G-d chose Jacob for Himself, Israel for His treasure." -- the Jewish people are called G-d's chosen here in T'hillim / Psalm 135:4.
Y'shayahu / Isaiah 42:4 is speaking of a time when "Neither shall he weaken nor shall he be broken, until he establishes justice in the land, and for his instruction, islands shall long."
Pay attention to the fact that the list maker has made eight claims time to chapter 42.
The claims, on the surface, may seem to have some validity -- but when the chapter is read from beginning to end it is clear that Isaiah is speaking of G-d and His relationship to the Jewish nation.
IN CONTEXT ask yourself:
The answer to the first two questions is "of course not." Jesus never taught in any islands, and no one outside of the Galilee and parts of Judah had ever heard of him. He was not mentioned by any historians of the era -- even though the Romans were meticulous record keepers. It does not matter if Jesus existed or not, but the fact is that there is NO mention of him by others who lived at supposedly the same time. Here is an interesting snipped from John E. Remsburg, in The Christ: A Critical Review and Analysis of the Evidence of His Existence in which he presents a list of contemporaries to Jesus who failed to mention him:
Josephus (a Jewish priest and later Roman historian who lived in the 1st century CE) mentions a few Yeshus (Joshua's) but the ones some missionaries point to as being about Jesus are considered by most scholars to be latter forgeries by Christian scribes. FYI< Josephus was born in 37 CE, after Jesus' supposed death -- so he was not a contemporary in any case -- he was a generation "too late."
Returning to the claimed prophetic passage, consider the context of the sentence from which the list maker took the "prophecy." The entire sentence reads "Neither shall he weaken nor shall he be broken, until he establishes justice in the land, and for his instruction, islands shall long."
During the lifetime of Jesus the Romans ruled and they were very cruel -- killing tens of thousands of Jews in cruel fashion. There was very little justice -- because of the Romans, not the Jews.
Philo lived in the time of Pilate (c. 25 BCE – c. 50 CE). He wrote in Legatione ad Caium of Pilate stating: "He feared they . . . might impeach him (Pilate). . .in respect to the his corruption, his acts of insolence, and his rapine and his habit of insulting people, and his continual murder of persons untried and uncondemned, and his never ending, and gratuitous and most grievous inhumanity."
And "so what" if Jesus taught? How is teaching a messianic prophecy? How many millions of teachers are alive even today? Teaching is hardly a messianic prophecy!
Likewise recall that chapters are a Christian invention -- chapter 42 does not exist in a vacuum (neither does Isaiah 53!). From chapter 40 through to the end of Isaiah (chapter 66) the prophet is speaking of the Jewish nation, it's special relationship with G-d, but how often the Jews are blind and deaf to Him -- resulting in exile, and also eventual restoration in the messianic age.
What of the claimed "fulfillment" passage in John?
John 12:20 - 26 is speaking of Jesus' death. It is not a prophecy that the messiah will come and teach (although the messiah will indeed be a great Torah scholar who will bring global knowledge of G-d).