Milhouse – Post mattan torah examples of kisuy harosh for men and married women as malbush (or da’as) yehudi.
Names given to children are traditional rather than “made up” as in those days in Mitzrayim.
But your premise is wrong, the yidden in mitzrayim HAD specific zchusim such as bris milah, eating meat and shchita, not intermarrying or serving Avoda Zara, belief in Hashem, keeping some form of shabbos, studying Torah (-v’es Yehudah shoach lefanav – to set up a yeshiva) etc.