Hebrew literacy was not widespread outside of the Jewish community, and the further one travelled from Jeruslaem the less Hebrew the Jewish community spoke and understood. But around Jerusalem and Judea Hebrew was the language of choice for the nationalistic Jewish community to whom Jesus was sent.
In fact, Jesus’ “eli, eli, lama sabachthani!” and numerous other Aramaicisms encoded into the Greek of the New Testament suggests strongly that the normal language of day-to-day conversation was Aramaic.
These few Aramaicisms were the exceptions not the rule. The fact that those few Aramaicisms were left untranslated in the Greek Gospels, ie transferred verbatim, is indicative that the language the Jews spoke everyday was not Aramaic. Otherwise why translate all the rest that Jesus and the people said to each other into the Greek but leave these few Aramaicisms untranslated???
The fact is that just because Jesus mixed some Aramaic into his Hebrew does not mean that He was now speaking Aramaic, anymore than those of us do today when we mix words from other languages into our everyday English. We are still speaking English.
It’s not just the direct quotes, which are ALL Aramaic. It’s also the fact that all of the puns and figures of speech recorded in Greek either work both in Hebrew and Aramaic or in Aramaic alone.
Straining gnats and swallowing camels, for instance, is a pun in Aramaic, but not in Hebrew.