I blame producer Albert Zugsmith. There might be an earlier example, but I think he started it all. Richard Matheson submitted an idea for a film to Universal Studios to be called The Shrinking Man. He wrote the screenplay, and also the novel based on the idea, which was published in paperback under that title. Zugsmith, the producer, evidently thought the title needed “punching up”, so he retitled it The Incredible Shrinking Man, which is how the film was released (Many decades later, Matheson finally changed the title of his novel to match, after years of being republished without the adjective, maybe because more people were familiar with the old movie). The film was released in the first half of 1957.
American International was a small studio that often made quick films to capitalize on trends, and Bert I. Gordon was one of their low-budget producer/directors who could bring in a splashy and trendy title quickly and cheaply. Universal made a movie about a guy who kept getting smaller and smaller? Okay, we’ll make one about a guy who keeps getting bigger and bigger. The Colossal Man. But we’ll need an adjective, too, so he became The Amazing Colossal Man. It was released in the fall of 1957. (The sequel, released a year later, didn’t use any adjectives except “Colossal” in the title).
This was, I think the start of a new trend – the Unnecessary Title Adjective. There was going to be a sequel to The Incredible Shrinking Man, to be called The Fantastic Little Girl, also written by Matheson, but it was never made. Producer Zugsmith later wrote and directed The Incredible Sex Revolution in 1966. We also got
The Incredible Mr. Limpet (1964)
The Incredible Petrified World (1961)
The Incredible Two-Headed Transplant (1971)
The Incredible Melting Man (1977)
The Incredible Shrinking Woman (1981)
There was also The Incredible Journey, based on the book of the same name, but I’ll argue that, in that case, the adjective was justified.
This overuse of adjectives was also picked up by Marvel comics. Before this you had Superman and Batman and Wonder Woman and The Human Torch and the Submariner and The Phantom and a host of lesser-known characters who did just fine without any adjectives to describe them. Superheroes got a revival in the 1957 at DC when the brought out a new, revamped version of The Flash and followed it up with others, including groups like Challengers of the Unknown and Justice League of America. But Marvel kicked off their revival with The Fantastic Four. There was that adjective again. They followed this up with The Amazing Spiderman and The Incredible Hulk and The Astonishing Ant Man (who appeared in Tale to Astonish) and The Mighty Thor. That’s the way they were heralded on the covers and splash panels. You never had The Mighty Superman or Magnus the Amazing Robot Fighter. Naturally, these adjectives carried over into TV versions and the movies. You didn’t just have The Hulk, it had to be The Incredible Hulk. It was The Amazing Spiderman.
Years later, to differentiate titles, Spiderman got a host of other adjectives, starting with The Spectacular Spiderman (a magazine-sized non-comics-code publication that ran for two issues in 1968; the title was re-used for a regular comic book starting in 1976).