
This is an unusual Jewish Y Male subclade. Most Ashkenazi Y-DNA branches are of Middle Eastern origin, but their nearest non-Jewish Middle Easterner links usually go farther back or are with Palestinians or Lebanese. J-ZS2102's main sibling branch, J-L859, is definitely associated with being descended from Qurayshi Arabs who came out of deep Arabia and participated in Muhammad's conquests—so these aren't Arabs whose recent origins are in lands closer to Israel.
There are many possible explanations for this connection. One, which is tempting given that its genetic "neighborhood" is so heavily Arabian, is that J-ZS2102, or its direct ancestor, entered the classical Jewish population in Judaea, via the conversion of the Idumeans, who were a part-Arab group from the desert fringe of southern Israel.
Another is that the Qurayshis descend from people who were in the Levant—maybe even early Israelites—around the year 1100 BCE, and made their way south to Mecca. For what it's worth, there are legends placing this Arab tribe's origins farther north. One decent reason to believe this might be true is that the closest connection that the Jewish J-ZS2102 branch has is not to an Arab branch, but to an Armenian. Another is that a member of the ancestral J-FGC11 branch was found in an ancient Canaanite skeleton in modern-day Lebanon, dating back 3,600 years—which might suggest that this "family" of lineages originated in the north, and then most, but not yours, migrated into Arabia.
This Y-DNA branch is a small lineage among Ashkenazim—by one count, it's #61 in size, and about 0.3% of Ashkenazi males belong to it. That's small, but, much smaller ones exist. Also: so far, we haven't found any non-Ashkenazi Jews in J-ZS2102, which probably means that it didn't arrive late in Eastern Europe from another Jewish community. In fact, one YFull date estimate says that the Ashkenazim in J-ZS2102 trace back to a common ancestor around 450 to 500 CE, which suggests that this lineage might've been around in the Ashkenazi gene pool from the very beginning of its development in Europe, and then before it, in Judaea.
Please join this group if you have been tested by FamilyTree DNA if you fall into this subclade to explore, learn more, get to know fellow cousins, and theorize.
(Thanks Josh Lipson for this information)