Akira Toriyama's Dragon Ball Z resonates with audiences of all ages for many different reasons, but it benefits from one of the shonen genre's most popular protagonists, Goku. Goku displays many stereotypical shonen protagonist traits, but Dragon Ball Z attempts to push the character out of his comfort zone through the bombshell revelation that he's not a human but a Saiyan, a warrior race of aliens. Goku's Saiyan heritage kicks off Dragon Ball Z and remains an emotional throughline across the rest of the anime and its sequel series. Saiyans are a later Dragon Ball development, but they definitely overwhelm the franchise's storytelling once they enter the picture.
Source：https://www.cbr.com/dbz-goku-kakarot-saiyan-heritage-acceptance-character-growth/
