Ah yes, Jesus largely taught the Jewish law, this was not an uncommon thing. Rabbis would do this often, in interpreting the Law.
He made some things more difficult, like declaring that lusting after someone was adultery.
He affirmed some interpretations of the Kingdom and Messianic expectation, but that is not to say He only did such, but also taught various lessons not only about morality or properly following the Law, but also about the Messiah and the relationship of Israel and God, and told of what would happen about the Crucifixion and what not.
Some teachings seem simple, while others are deeper. However, even simple things may not be as simple as you might think! He not only taught properly understood wisdom, but also His actions achieved much, and nowadays some of it is difficult to understand without the proper Jewish understanding of the time.