And Goku isn't Japanese either; he is Saiyan, an Alien race.
> Race, in general, isn't a big deal when you are younger
It isn't a big deal, if you're not impacted by it (colloquially known today as 'privilege').
However, what you might not believe is a big deal, is arguably a big deal to other people.
A few examples:
You may not be aware that black women in the US are 3-times more likely to pregnancy related issues than white women. There is a downstream impact on the children of those women. [1]
Separately, there still exists a serious gap in achievement for Alaska Native / American Indian children.
1: https://www.cdc.gov/healthequity/features/maternal-mortality... 2: https://www.nsba.org/ASBJ/2020/December/condition-native-ame...