Are Egyptians considered Arab by ethnicity or do they just follow the language and religion?

Answer 1

It is because Egyptians have been Arabized, meaning that they follow the language and culture of the Arabs who invaded, that Egyptians are ethnically Arab. They do not have genetic roots to Arabia, if that is what the question is asking.

Arabs, Turks, Magyars (Hungarians), and numerous other ethnic groups are not actually homogenous. They are composed of two historical groups that intermarried and created a unified culture. In the Arab case, Arab nomads from Arabia conquered Egypt and brought it under their rule. During that period, those Egyptians who converted to Islam began to take on the same mannerisms as the foreign Arabs who had conquered them. They began to speak the same language, dress in the same clothes, and believe in the same general ideologies. This process is well-documented by Arabs and is called Arabization or Ta3arib (تعريب). This is why the Jews and the Christians of Egypt (such as the Copts) often do not consider themselves Arabs. Unlike their Egyptian brothers whose conversion to Islam made them more susceptible to Arabization, they retained their pre-Arabized ethnic sensibility. Therefore, although Egyptians call themselves Arabs, the majority do not and should not have lineages that go back to Arabia, but to pre-Arab ancestors in Egypt, likely Jews, Christians, and Pagans in the Byzantine Empire.