I still think when it comes to x superhero being made by x nationality, it feels a lot more authentic than if x superhero’s conceived by writer of y nationality. Maybe not always the case but still. I remember somebody saying that the problem with Captain Britain’s that he doesn’t feel authentically British.
Actually and parsimoniously, it’s safe to say a good number of British superheroes are practically derived from their US counterparts. Captain America gave way to Captain Britain, Spider-Man’s got a feline counterpart in Leopard of Lime Street. Marvelman owes a lot to Shazam (given some of his earlier stories were based on the latter’s).
That’s not to say the British or any other nationality can’t come up with their own superheroes. They did to some extent but I think 2000AD’s Vigilant gives a better idea of what a British superhero team were truly like (chances are some of them come from much unlikelier sources). Excalibur if I’m not mistaken still had American members in it.
For another matter, Peni Parker seems like a Westerner’s idea of what a Japanese Spider-Man could be like but with Toei Spider-Man being the real thing (made in Japan, feels like Power Rangers with Spidey taking on actual monsters). Power Rangers is practically close to the Japanese take on superheroes but because it’s based on those productions.
I haven’t read My Hero Academia yet but I feel as if the original Japanese productions give a better idea of what the Japanese take on superheroes could be like with 2000AD’s Vigilant being the British answer to this.