After all, Jesus was Jewish.
Discounting the trinitarian nonsense that Jesus is God, which is contrary to anything found in scripture.
The scriptures prophesy a Messiah who would:
A. Be rejected by his people and give his life to save them from their sins.
B. Restore the kingdom of Israel and save them from their enemies.
The Jews accept ‘B’, but do not understand the need for ‘A’.
They believe that their salvation depends on keeping the Law of Moses. They fail to recognise that the Law of Moses condemns them to death because no one can keep the Law 100%.
This means that Israel first need saving from their sins.
Because Jesus did not accomplish ‘B’, they refuse to accept him as their Messiah.
Why Jews don’t accept Jesus as the Messiah
What is the Messiah supposed to accomplish?
The Bible says that he will:
A. Build the Third Temple (Ezekiel 37:26-28).
B. Gather all Jews back to the Land of Israel (Isaiah 43:5-6).
C. Usher in an era of world peace, and end all hatred, oppression, suffering and disease. As it says: "Nation shall not lift up sword against nation, neither shall man learn war anymore." (Isaiah 2:4)
D. Spread universal knowledge of the God of Israel, which will unite humanity as one. As it says: "God will be King over all the world—on that day, God will be One and His Name will be One" (Zechariah 14:9).
The historical fact is that Jesus fulfilled none of these messianic prophecies.
Christians counter that Jesus will fulfil these in the Second Coming, but Jewish sources show that the Messiah will fulfil the prophecies outright, and no concept of a second coming exists.
I hope you find this helpful.