"Micah 5 only means the Messiah is from David's family"
The claim, stated fairly
Bethlehem in Micah 5:1 stands for the house of David; it is about lineage, and "from of old" means an ancient dynasty.
Micah names a town and a ruler "whose goings forth are from of old, from ancient days".
The Targum on this verse says "from you the Messiah will come forth before me". In Matthew 2:5-6 the chief priests and scribes give Herod Bethlehem as the place, from this verse.
The phrase "from ancient days" (mimei olam) is used elsewhere of God's own antiquity, which is why Messianic Jews read it as pointing beyond an ordinary descendant.
The text
1וְאַתָּ֞ה בֵּֽית־לֶ֣חֶם אֶפְרָ֗תָה צָעִיר֙ לִֽהְיוֹת֙ בְּאַלְפֵ֣י יְהוּדָ֔ה מִמְּךָ֙ לִ֣י יֵצֵ֔א לִֽהְי֥וֹת מוֹשֵׁ֖ל בְּיִשְׂרָאֵ֑ל וּמוֹצָאֹתָ֥יו מִקֶּ֖דֶם מִימֵ֥י עוֹלָֽם׃
1But thou, Beth-lehem Ephrathah, Which art little to be among the thousands of Judah, Out of thee shall one come forth unto Me that is to be ruler in Israel; Whose goings forth are from of old, from ancient days.
WEB/WMB: But you, Bethlehem Ephrathah, being small among the clans of Judah, out of you one will come out to me who is to be ruler in Israel; whose goings out are from of old, from ancient times.
Micah 5:1 (Hebrew, JPS 1917, WMB) · English Bibles: Micah 5:2
In the New Covenant
4Gathering together all the chief priests and scribes of the people, he asked them where the Messiah would be born. 5They said to him, “In Bethlehem of Judea, for this is written through the prophet, 6‘You Bethlehem, land of Judah, are in no way least among the princes of Judah; for out of you shall come a governor who shall shepherd my people, Israel.’”
Matthew 2:4-6 (WMB)
Where scholars disagree
Mimei olam can also mean "from long ago" in a human sense (Amos 9:11 uses it of David's fallen booth). The birthplace point does not depend on it.
Sources
- Targum Jonathan on Micah 5:1
- Amos 9:11
- Hebrew: Westminster Leningrad Codex. English: JPS 1917; World Messianic Bible (public domain).