Like most really early animated characters, Mickey Mouse was a lot of things over a long period of time. And as far as American animation goes, Mickey Mouse has been a staple for the childhood of literally every generation. Younger millennials and zoomers grew up on Mickey Mouse Clubhouse. Children in decades prior watched Mickey be a musketeer in one short and starving due to poverty in the next.

So while the rough edges of the character have been sanded down over time, he's still very much a plucky, brave, kind, and helpful protagonist in most of the media he's in.

Which to your average adult viewer means... he's a bland and uninteresting character.

That said, he's still an icon of animation as a whole, and most things with Mickey in them are doing some new and novel something (design, production pipeline, whatever) that pushes the whole industry forward in some way.

Exactly. Donald Duck is an infinitely superior character.

Rich Evans once said of Who Framed Roger Rabbit: "Bugs Bunny gave Eddie Valiant the spare tire (instead of a spare parachute) because Mickey Mouse would never do anything funny."

I think Mickey just serves as a stand-in for Disney in general

I mean... He was literally the first animated character ever to have synced audio with the visuals.