For whatever it’s worth, I was scared of clowns as a child, but I always assumed that the scariness of clowns was exactly the same as the scariness of Disney park performers, Mall Santas, and those, like… staff in some historic houses turned into museums, who do their job in character and in period costume
i.e. I thought the scary thing was “a stranger is trying to interact with me while pretending to be something they are clearly not.”
which is a perfectly reasonable thing for a small child to be afraid of! kind of a basic survival skill really
and judging by, like, every photo I’ve ever seen of a kid with a mall Santa, the instinctive fear response is equal between clowns and other professions who do that same scary thing
But somehow with clowns, most people never grow out of it?
Idk