Truth of the matter, you can have many characters with similar (even identical) powers and they can all tell original stories of their own. Colossus is nothing like The Thing which is nothing like The Juggernaut. But their powers are extremely similar.
The moment you need to "use" an established character mantle is the moment you admit the character you created does not stand on its own. I dare Marvel to change Miles Morales hero name to something else and then attempt to sell it.
Well, that's the thing, these characters were never supposed to have a "mantle" to begin with, their costumes and hero name sake just as much as a part of the character, they are not interchangeable. Spider-man IS Peter parker, Captain America IS Steve Rogers, Iron Man IS Tony Stark, because it was these characters who went throught the tribulations and triumphs that makes part of what it is to be a hero (in fiction that is).
Power settings and costumes have nothing to do on why people like a character, you need the whole package, which means you can't just give the same set of power and costume to another character and expect the same result, because you will get this:
In the original game, they didn't need to specify that Spider-man IS Peter Parker. And yes, I'm aware that there was a comic series called "pter parker: Spider-man" and it was a vanity project Marvel did to keep Todd McFarlane happy to be the writer and artist of the book, problem was that McFarlane can't write for shit, and soon we would go and do his Spawn comics anyway.
And shit, even Super Heroes that were supposed to be a "title" or a "mantle" to be passed on, have a lot of problem to introduce new characters. Fuck, for over a decade the DC boys bitched about Hal Jordan being evil and gone and how much they hated Kyle Rayner and bitch bitch bitch, till Geoff Johns came along and brought Jordan back. And the funny thing is, Hal Jordan wasn't "THE" Green Lantern, he was "A" Green Lantern, and he wasn't the only Human Lantern either, Guy Gardner and John Stewart were already kicking around long before Rayner showed up. But the way DC set it up was to Rayner to take Hal's place, and in the reader's mind, Hal Jordan IS the Green Lantern.
And that was in the 90's, comics have been trying this "pass of the mantle" shit for decades now, way, WAY before this "All-New, All-Different Marvel" shit from 2015, with mixed to little sucess.
And in a business way, it is understandable, you gotta refresh the IP for a new generation and for the creators is a way to get their hands on royalties. Bit of a snag here though, capeshit comics audience ain't getting renewed, capeshit comics is being read by old farts that want the old characters back, the younger audience might watch the movies, but they read manga and webtoons, and so the characters from the fucking 60's have to keep coming back.
And it ain't just the case of old VS new characters, but the utter clusterfuck that is comic continuity, and even new Characters like Kamala Kahn for example, they might be new, but they are still pigeon held to a old and confusing universe, the origin of her powers for example comes from the Inhumans... who the fuck knows who the Inhumans are for starters?
DC does a lot of reboot, but still keep their assload truck of characters around, but they mitigate the damage by doing a lot of issues that are just "the caper of the week".
Marvel though? that shit is utterly insane, I used to think that I was somewhat versed in capeshit to at least enjoy a comic here and there and get the gist of it, and I went on to read some of the new X-men issues and that shit is beyond comprehensible, no wonder there are a lot of rumors that Marvel will bite the bullet and reboot the whole thing. Shit thing is, we already seen modern Marvel doing a clean slate universe, and it didn't end well.
Honestly I don't think this problem has a solution. As I grow older, one thing keeps getting certain to me, everything has a time and place, and that goes for fiction and art.
Ever saw one of the new Simpsons episodes and noticed how weird and wrong is to see Bart Simpson with a smartphone? i get the feeling that even if someone who never saw The Simpsons before would say that looks wrong, because the Simpsons is from the 80's and 90's, it's characters and iconography don't fit with the present we have.
Same shit goes for Super Heroes, maybe they can be more malleable because it is can be more about the characters and not the time period, but not for over half a fucking century, because you will wear down the character to the point that prettymuch every single support character in the Spiderman comics already has/had spider powers (or a symbiote). The energy behind "the big two" comics is that they are tired, old and "Simpsons Already Did It" vibe.
And capshit movies and series might be heading there, sooner of later, because for one thing I can say is that the dialogue of these Marvel flicks are getting dated as fuck, because whenever I get the sight of their quippy banter in other stuff, the first thing my mind says is: "this is so 2010, Jesus."