He's funny af to me, also a lot of people who complain that he is dumber haven't watched the subbed dragonball. For people who have seen the dub he has more of a generic superhero personality. but, in japanese even with the dialect of japanese he speaks, he is characterized as a country bumpkin mostly shown in the way he stretches the end of his sentences out and mispronounces stuff. He is that way because he grew up only ever knowing his grandpa on Mt. Paozu until he was like 12. So the way he acts and is portrayed in the subbed version is the true Goku, a country simpleton, who's only life goal is fighting strong people and growing stronger.