When I was a kid I had a book called Origins of Marvel Comics, and a bit later one called Son of Origins of Marvel Comics. That second one sounds a little tongue-in-cheek now that I think of it. As you might guess they were about the beginnings of the first popular Marvel Comics characters in the early-mid sixties.*
The thing I want to emphasize is that, yes, it featured reprints of the first and/or origin stories of the superheroes, as well as sometimes another reprint from slightly later in development. But on top of that there was Stan Lee's reminiscences about how the ideas came to him, and his collaborations with Marvel's art staff.
Lee is often accused of giving himself too much credit in the creation of the Marvel Universe. For diehard fans of Jack Kirby and sometimes Kirby himself, any credit given to Lee was too much. I wouldn't agree, but there's definitely an element of self-mythologizing in these books.
Around the same time I had another book, analogous, on the creation stories of DC Comics superheroes. It's similarly rich in the number of characters, and they're colorful characters. But this was more of a historical telling. No one person could give a firsthand account of all these creations and say, "Yeah, I had a hand in all of them." Not even fraudulently. It wouldn't have been credible. A couple of them hadn't even started at DC. **
To the extent I have a point here, it's not about whether Marvel or DC is/was better. It's that people have a tendency to be sucked in to big stories, not just about fictional characters but also their fictionalized idea about the real people behind them. That's why you hear a lot of things that are too "good", too simple, to be true.
*The company had been around since the thirties, and the characters Captain America and the Submariner predated American entry into WW2, so this was really more a highly successful rebranding than anything else.
** Plastic Man was one of the big successes at Quality Comics, a company that didn't long survive the industry downturn of the early fifties. The "Shazam!" version of Captain Marvel came from Fawcett Comics. DC had taken him out with a frivolous lawsuit and then revived him in their own pages about 20 years later.