Hello,
I would say I do not agree with Bro Nouman Ali Khan and the explanation given. Prophet Musa was someone who was raised not in an Israelite environment, under the Pharaoh. The statement "O my people" makes a lot of sense, as it is reinforcing his identity as a citizen of Israel, despite being raised in a non-Tauhid setting.
As of Nabi Isa, the Hebrew ethnic identity and citizenship is totally dependant upon the MOTHER, NOT THE FATHER. He spoke with authority and firmly to his own people, calling the segment of Pharisees "A brood of vipers". He could only be firm like this to his own people. His greatest challenge was that the Pharisees were presenting themselves as "Gods people" (Ummah) based on their ethnic identity as a Jew. This is the theme of the Injil by Isa, Paul, Peter and others... the challenging of this ethno-centric misconception, with the Ummah being presented in the Injil as extremely inclusive, even the non-circumcised Roman empire being a part of the Ummah, based upon repentance and faith in the God of Abraham.
Wasalam
Zack