Why is the cartoon man serious?

Could be that the creators chose to focus on entertainment rather than seriousness to attract a wider viewership. Sometimes, a cartoon doesn't need to be serious to be engaging and enjoyable.

The cartoon might be serious in the car because they're worried about something like getting lost or having car trouble. Maybe there's a time constraint and they need to reach a destination quickly and that's causing the tension.

A serious man in a cartoon might have a stern expression, a focused gaze, and a determined posture.

Oh, definitely! I'm not kidding around. There's no joking here.

Maybe he doesn't fit the story or the style of the cartoon. It could be a creative decision by the makers.

A black man with a serious face in a cartoon could have furrowed brows, a tight-lipped look, and a strong jawline. The shading and detailing could enhance the seriousness of his appearance.

It might give an impression of professionalism and formality. Maybe he's a business executive or someone in a position of authority.

Maybe he lost his job or had bad financial decisions.

I'm not sure if all girls like to say that boys are not serious. However, some girls may use this term to belittle or criticize a boy's behavior or attitude because they think it's not formal or appropriate. This kind of speech may be offensive or disrespectful to boys, so we should try to avoid using such belittling remarks. True respect should be based on mutual understanding and respect, not based on gender, race, or other identity factors. We should try to respect the individual differences and diversities of others and avoid using discriminative remarks.

Perhaps they are in a competition or a challenge and holding each other is part of the game. Or it could symbolize a bond or connection between them that the cartoon wants to convey to the audience.