There are people who have the Jewish heritage.. ie.. culturally etc.. but actually aren't into Judaism. A Jewish person who is into Judaism that I knew of would say these kind of people are NOT Jews.
Anyway, there were in the New Testament, Jews who saw Jesus and said this IS the Messiah. They got saved.
John_8:31 Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed;
John_11:45 Then many of the Jews which came to Mary, and had seen the things which Jesus did, believed on him.
John_12:11 Because that by reason of him many of the Jews went away, and believed on Jesus.
Acts_14:1 And it came to pass in Iconium, that they went both together into the synagogue of the Jews, and so spake, that a great multitude both of the Jews and also of the Greeks believed.
But here is the thing..
A Jewish person into Judaism is not worshipping the same God as christians! They were up until the New Covenant.. the New Testament.. then with the New Covenant, they didn't believe in Jesus who IS God.
So they wouldn't be saved if they reject Jesus.
The Messianic Jew I think would accept the New Covenant.. the New Testament.. recognising that OT prophecy from the Torah is about Jesus. Although I know there are messianic Jews who only accept the NT parts of Matthew Mark Luke and John and reject the rest of the NT.
So there are the Jews that get saved by believing in Jesus.
Then there are the Jews who are also into Judaism. Not many of these people get saved.