Jewish personal status originates in sacerdotal priestly hereditary status in ancient Sumer as still maintained by the Mandaeans. With the collapse of the last Sumerian state in 2004 BCE did Abrahamic EN (sacerdotal) refugees flee to Canaan, the holy land of the Sumerians. Centuries later did these Sumerian-Canaanites ENs establish themselves in Egypt as priests and their descendants eventually became the core of monotheist Atenism in Egypt. With the collapse of Atenism in the 14th century BCE did they have to flee once more to the holy land, to Canaan. In the ensuing centuries did the Atenist priests who became known as the Levites convert the peoples of Canaan to Atenism yet the tribal peoples of Canaan long maintained a syncretic mix of Canaanite polytheism and Atenist monotheism. With the conversion of the peoples of Canaan and their assimilation to Atenism was priestly sacerdotal status for the first time conferred to ordinary people beyond hereditary priests. This was a revolutionary development in the history of religion.
Different denominations of Judaism have different rules for conferring sacerdotal status on new converts. Matrilineage is only two thousand years old and before that was patrilineage the rule in the Southern Jurisdiction of Judah as still in Karaite Judaism, also in the Southern Jurisdiction of Judah. Core Median Judaism in contrast generally requires dual Jewish parentage for interited Jewish ancestry. Mandaeism still limits membership to its sacerdotal caste and does not accept converts, at least not overtly. Some denominations of core Median Judaism accept converts (Alevism, Alianism, Bektashism, Khaksarism, Sabbateanism and Yarsanism) while the others (Alawism, Druzism and Yezidism) do not, at least not overtly so. The rules and ceremonies for accepting converts are man-made, historical and yes completely arbitrary. Most denominations of Median Judaism are not bound by the Torah (Pentateuch) since Median Judaism is pre-Torah as the Torah was only written in the 6th century BCE and the people of the Northern Kingdom of Israel were deported by the Assyrians already in the 8th century BCE, two centuries before the Torah was composed. Anyway are the Rabbinic rules for “who is a Jew” certainly not based on the Torah but on the Talmud which was composed from the 3rd to the 6th century CE. Yet the rabbis of the Talmud (rabbis Akiva, Eliezer and Shimon recognized Median Jewry as heretics (i.e. sinners) although fully Jewish.
The mainstream Orthodox Rabbinic recognition of Ethiopian Median Jewry as full Jews is revolutionary since it affirms the Jewishness of Median Jewry and the validity of ancient conversions of Median Judaism despite not conforming with much later Halakhic standards that were yet to be invented.
In short, who is a Jew is a social construction, the Jewish people is a tribal Fourth World indigenous nation which is shamefully and tragically fragmented in its practices of tribal initiation in perniciously socially excluding one another. It is a great challenge to unite the Jewish nation through Aliyah (immigration), klita (integration) and interdenominational religious dialogue within the wider Judaism as based on education and profound knowledge about the heritage of Esoteric Judaism, i.e. Crypto-Sumerianism.
The Israeli Supreme Court has recognized non-Orthodox Rabbinic conversions as valid for the purpose of Aliyah to Israel. There is no doubt that conversions of Median Judaism are also legally valid under Israel’s Law of Return.