"There was no need for Aramaic, because the next
people He was to share the truth with were the Gentiles. Greek would have been
the best language to use to reach them with."
Jesus was a Jewish Rabbi who never gave up his Judaism.
While the small wealthy class in Judea generally spoke Greek, the masses were
basically illiterate and spoke Aramaic. Less than 10% of the population
was literate and even that 10% was just barely literate. Jesus message was
never ever to the gentiles. You are confusing him with
Saul/Paul.
Jesus sermon on the mount was to five or six thousand people
and they were basically from Jerusalem and spoke Aramaic.
It was the apostle Saul/Paul - the Roman, who changed
everything from the Sabbath day to the message for the gentiles. Something
Jesus never did.