To pick up where I left off, for part II:
Jews are a nation — not to be confused with a modern “nation state” (e.g. the United States, Canada). That is, a community of people with a shared language, history, ethnicity, culture, and/or territory. They have a collective identity as a singular people (i.e. the Jewish People, the People or Children of Israel) that goes back 3000 years.
Case in point: the term “Jew” is a modern English sixteenth century translation of the Old English word “Iudeisc,” which in itself was a translation of the Latin word “Iudeas,” meaning a citizen of the Kingdom of Judah (930 BCE-587/6 BCE) or a citizen of Judea (586/7 BCE-136 CE). In most languages — including Hebrew, the ancestral language of Jews — the term “Jew” is quite literally still the same word as “Judean.” (As in Judea, that place we now call The West Bank.
So their identity as a nation very much surpasses their identity as a religious group. In fact, the understanding of Jews as a “religious group” is a rather recent development in history, dating back to the French Revolution and the Enlightenment.
(Also another thing, I see a lot of MNs get confused about this aspect often, so to clear this up - whether a Jew believes in Judaism or not is fully irrelevant, because they are still a member of their nation).
The Jewish People are the direct descendants of a confederation of Hebrew tribes that lived in the region of modern-day Israel/Palestine during the Bronze Age. For 3000 years, they have called themselves a tribe. In fact, the term “tribe” in English comes from the Old French “tribu,” which was first used to describe “one of the twelve divisions of the ancient Hebrews.”
None of this is a matter of religious belief or imagination; their tribal identity and ancestry is among the most well-documented in the world. Genetic studies on Jews clearly indicate ancient Canaanite heritage (the Hebrew tribes emerged from Canaanite tribes). Much of their culture still reflects ancient Canaanite culture; e.g., Hebrew is the only Canaanite language that still exists to this day, and many Hebrew words still allude to the ancient Canaanite gods (for instance, the generic Hebrew word for god — as opposed to THE god — is “el.” El was one of the two most important gods in the Canaanite pantheon).
Because of imperial conquest and colonization, most Jews don’t know which of the Hebrew tribes their ancestors came from, though if you are Jewish, you most likely descend from the tribe of Benjamin, Judah, or Levi. Ethiopian Jews claim descent from the tribe of Dan. Samaritans, who are Israelites but not Jews, descend from the tribes of Ephraim, Manasseh, or Levi.
Everyone is indigenous to somewhere (or somewheres). Not all peoples are Indigenous Peoples.
The United Nations Permanent Forum on Indigenous Issues defines Indigenous Peoples as the following: (1) self-identification as Indigenous Peoples; (2) historical continuity with pre-colonial and pre-settler societies; (3) strong link to territories and surrounding natural resources; (4) distinct social, economic, or political systems; (5) distinct language, culture, and beliefs; (6) non-dominant groups of society; (7) resolve to maintain and reproduce their ancestral environments and systems as distinctive peoples and communities. The Jewish people tick every one of these boxes.
Indigeneity is primarily about land-based, cultural continuity that predates colonialism and imperialism. Their culture; their belief system; their language; their social systems (e.g. Kohanim, or the inherited Jewish priestly class, not to be confused with rabbis); the Jewish people’s understanding of themselves as a people, as a tribe, and as a nation: all of these characteristics long predate the foreign conquests of the Assyrians, Babylonians, Persians, Greeks, Macedonians, Romans, Byzantines, Arabs, Crusaders, Ottomans, and British.
The fact that they’ve been able to preserve the culture and identity of their ancestors in the face of so much conquest, oppression, ethnic cleansing, slavery, massacres, genocide, spiritual repression, and more is nothing short of remarkable and an example of Indigenous resistance.
An ethnic group or ethnicity is a social group that shares common ancestry, culture, traditions, history, language, and/or religion, as well as a plethora of other commonalities. Ethnic groups have what is known as an “ethnogenesis,” meaning the point at which an ethnic group forms or develops. For example, the ethnogenesis of the ancestors of today’s Jews, the Israelites, can be attributed to the point in time during which a confederation of Hebrew tribes united to establish the Kingdom of Israel some 3000 years ago.
Ethnic groups can both merge (known as a pan-ethnicity) or split into groups (known as sub-ethnicity). Because of their forced displacement, which resulted in geographical distance from each other, various Jewish sub-ethnic groups formed. Some examples of Jewish sub-ethnic groups are Ashkenazim, Sepharadim, and Mizrahim.
This bit is germane to what you were querying: For thousands of years, Jews have practiced endogamy — that is, marrying within the ethnic group. Because they have had such a closed genetic pool for so long, Jewish DNA is among the most studied in the world.
And also, another significant factor that plays into all of this - Judaism differs from the other Abrahamic monotheisms, Christianity and Islam, in that it is the only one of the three that never created or sought to create an empire. So despite the fact that while most Jews were forcibly displaced from their homeland by invading empires at various points throughout history, they didn’t go out into the world to conquer and appropriate from others (again, see the Christian and Islamic empires who did do this), and as a consequence there was a lot less “mingling” (for want of a better word) with other peoples or ethnic groups. Instead, Jewish culture, spirituality, and identity remained tethered to the Land of Israel through prayer, language, customs, and more. This is evident in things such as their holidays, which celebrate the earth of the Land of Israel; the Hebrew calendar, which follows the agricultural cycle of Israel/Palestine; their prayers, which call to Israel; the preservation of the Hebrew language in various Diasporic dialects such as Yiddish and Ladino; etc.
Hope that helps.