TYB
>Why then, does everyone say that Jesus was a Jew?
He´s considered of the tribe of Judah. Tribe of Judah = Jews.
Just saying "Jews" came from the tribal name, and yes, also Israelites like the other tribes. If modern Jews are actually Edomites is another question.
I haven´t looked deeply into this, but it´s interdasting. I´ve mostly been trying to trace the lost tribes up north to Scythians and such. Ralph Ellis has interesting theories, both about Jesus identity, but also about OT stories actually coming from Egypt. David, Solomon and more actually Pharaoes. Search for him on youtube.