Jesus was probably fluent both in Hebrew and Aramaic and chose which language to use depending on where he spoke and to whom he addressed.
During the first century AD, Hebrew was the upper-class tongue in the Holy Land while Aramaic was the common man’s language. When Jesus spoke to the meager of the earth he is most likely to have spoken Aramaic. When he addressed fellow theologists and Jewish scholars in Synagogue, he probably spoke Hebrew.
Bonus Fact: Both in Hebrew and Aramaic Jesus’ name is pronounced ‘Yeshua’, which literally means salvation. However, it is most likely not a theophoric name, but probably his given name. ‘Yeshua’ is an abbreviation of ‘Joshua’ which was a very common name in the Galilee area in the st1 century BC and following Century, that is to say exactly in the times when Jesus was born.
Mind you, ‘Joshua’ means: ‘God will save us’.