>>11338078
My completely unresearched and likely inaccurate take:

Western art and japanese art feature a lot of focus on strong, tough role models (ie superheroes) and by extension muscular realistic builds suitable for gritty tough story settings. Outside of that, where they differ is in the cartooning aspect, specifically what they tend to exaggerate. Western cartooning is mostly aimed at either children or political audiences, and any/all aspects of a character tend to get exaggerated for effect to readily convey the impression a character should give off. Japanese cartooning is aimed at a wide variety of audiences, but the exaggeration is almost entirely focused on neotenous features (e.g., big eyes, cute faces, all anime girls are cats, etc) while the rest is generally handled in a way that is at least somewhat grounded in realism.

The companies/individuals who pioneered a lot of how modern commercial art is done (and the character designs they created) likely had a big and lasting impact that later generations recycle without questioning it because they grew up on it and it's just what cartoons *are* to them.

There's probably also a cultural/legal aspect to it too in that western characters need to be sufficiently distinct from each other (and from reality) to be trademarkable, while japanese characters lean more into common/trope-y features so you get more similarity in terms of design traits across franchises.