if you didn't have the Jewish understanding of any messiah you wouldn't be able to make any future messianic concept from the text. Show me where the text refers to any future leader as "the messiah."
That's like saying two things are the same thing because they have the same name. Messianic Judaism and Christianity have the same essence but to an extent they are different faiths. Jesus Is the God of Christianity | Jewish Voice
The concept of a Jewish Christianity is foreign to Jewish People because most of them are raised with the notion that the Yeshua of the New Testament is only for Gentiles. Jonathan Bernis notes:
The lie that Jesus Christ is the God of Christianity is the concept I was raised with. For me, there were two groups of people in the world—Jews and Gentiles, or Christians (we generally perceived them to be the same). We had our God – the God of Israel – and Christians had their God, Jesus Christ, the son of Mr. and Mrs. Christ. And somehow this Jesus-God was a child who had become God.
I was also taught that Christians believe in three Gods: the Father, the Son, and the Holy Spirit. This, too, is a deception and a stumbling block for Jews, who, even if not religious, know one thing: God is One.