1 The midrashic claim(*) that the Jews were redeemed from Egypt because they kept their language, their clothing, and their names
2 The assertion of the Zohar(?) Jews were at the 49th level of Tumah and had to be redeemed immediately because they if the reached the 50th level of tumah they could never be redeemed.
I suggested the following. The language, clothes, and names meant that the Jews still had their common tribal identity. They recognized one another as being part of their group, and that others were outside the tribe. The 49th level of tumah indicated that the Jews had nevertheless assimilated bad middot from the surrounding culture, as shown in the example of the Jews who betrayed Moses to Pharaoh after the killed the Egyptian, as well as the character flaws caused by slavery and oppression that came out in the desert.
Basically, the Jews remembered who they were, but not what they were supposed to be about. That is why they had to be redeemed from Egypt, isolated in the desert, and retrained in what being a Jew was supposed to be about.
(*) There actually is no Midrash that says all of this in one place. See the excellent article by Rabbi Elli Fischer https://tinyurl.com/ybqzxnzy for details.