Hebrew was the common language of Jews in Judea, but not in Nazareth (Galilee). The two languages are unrelated, and though Jesus was certainly able to speak and understand Hebrew, His mother tongue was indeed Aramaic.
Since you mentioned an interpreter (unnecessary, BTW...anyone who doesn’t understand what is being said can have a Missal right in front of him), I thought I’d tell you that for the first time in my life I’ve been able to see what truly bi-lingual people experience when they listen to one of the languages they speak. While the Ordinaries of the Mass (those are the parts that do not change from week to week) are being sung, I no longer have to translate them; I am able to understand the LATIN without switching it back to English. It’s quite an odd feeling, actually...very weird.
Unfortunately for me, Latin was removed from most school curricula just as I was getting into high school. Thankfully, the tide has turned, and my own son’s (Catholic) high school offers a solid four-year curriculum in Latin. HE will truly “speak Latin.” My own knowledge is due entirely to exposure in church and in literature.
Regards,
Hebrew and Aramaic are not unrelated. They are two partially mutually intelligible branches of the Levantine Semitic language family. However, to really make your point, the evidence which was once cited to suggest that the gospels were late-second-century forgeries is now interpreted to show that the evangelists’ Jewish society was immersed enough in Greek as to use it as a lingua franca; St. John was a Jew who composed his thoughts in Greek when he wrote.
Further, the use of two languages, or at least tonalities, in a society is actually more common than America’s use of only one. Typically, there is a formal language and a colloquial language. For instance, Most of the third world uses a colonial language for literature, government and commerce, while retaining a local language for informal conversation. The entire Muslim world reads Arabic, but speaks local languages; In Europe, Jews read Hebrew, but spoke local languages, giving rise to Yiddish when German and Hebrew intermingled. In Japanese, the written characters have no relation to spoken characters, and an entire new set of characters were created to translate spoken characters to text.
Even in traditional English, Anglo-Saxon was “common” and French or Latin, “cultured.” Hence, the middle-men would, for instance, kill “sweine,” “cattle,” or “deere” (Anglo-saxon) and present it to the Lords as “porc,” “beouf,” or “venisson” (French).