It meant that they could return to Judea and rebuild the Temple with the full backing of the Persian empire. See Isaiah 45:1 ("Thus said the Lord to his Messiah (Maschichu = his Messiah), to Cyrus, whose right hand I have holden to subdue nations.")
Mashiach just means an individual anointed by God to fulfill a particular purpose. It had no connotations of divinity before Pauline Christianity.
*chuckle* No, not quite. Belief in a Kingly Messiah ben David in the 1st Century is well attested in the Talmud, Apocrypha, and Essene literature. Though I like your attention to Isaiah's prophecy.
Mashiach just means an individual anointed by God to fulfill a particular purpose. It had no connotations of divinity before Pauline Christianity
Not entirely true. You might want to read this article from the Jewish Encyclopedia to get a broader view on the topic and then, if you have the resources, dive into the Talmudic and Midrashic material cited. The idea that the Messiah would be just a man, albeit one endowed with wisdom from Hashem, is actually relatively recent, and developed largely in response to Christian claims.
It's true that you don't find Deity directly ascribed to the Messiah in the Judaica, but there are plenty of references to a quasi-divine Messiah to go on.
In any case, it has never been the belief of either Messianic Judaism or orthodox (not Orthodox, if you know the difference) Christianity that Yeshua is the entirety of Hashem incarnate. That would be ridiculous, of course. As Messianics, we find that the easiest way to explain the relationship is to postulate that in Yeshua, the Holy One placed His Sh'khinah into a Man to undertake His ultimate plan of redemption. Another way to look at it is that Yeshua is the living incarnation of the pre-existent Torah (the Word of God, to use John's terminology). I've got an article exploring this idea in brief here if you are interested.
For the record, I want no Jew to become a Christian. I will not take part in the assimilation of any Jew, whether to Christianity or secular American society. I do look forward to the day when all Israel is reconciled with Yeshua the Messiah just as the brothers of Joseph were reconciled to him, but I want any Jew who professes belief in Yeshua to become more zealous for the Torah, the traditions, and our people, not less. My children, for example, are Jews, and will be raised to be Jews. My nine-year-old daughter lit the second light of Hanukkah tonight, saying the traditional prayers.
Shalom and Hag Hanukkah Sameach!