Though not the first color movie, The Wizard of Oz left an indelible mark. Swapping from the old world of black and white to color the world flew over the rainbow. Movies have never been the same since.
Kalmus, an MIT alum, created a process for color movies and ramped up a company, Technicolor. Initially, there was little interest in the added expense of color films; color movies did not attract significantly larger audiences.
Eventually, Walt Disney bought a short-term exclusive user contract for some period of time and released color cartoons. Exclusivity ended in 1935 but Disney continued using the process, releasing Snow White, a blockbuster, in 1937.
The Wizard of Oz and Gone with the Wind (both 1939) created an expectation of color movies.
Mainstream color movie predated mainstream color still photography. With their large audiences, movies justified the cost of color processing whereas still photos did not.
Color movies were technically difficult to create correctly. To ensure quality, Herbert’s wife Natalie worked with movie studios. Her role at Technicolor resulted in an enormous 400+ credits on IMDB.
Eventually, Leopold Mannes and Leopold Godowsky, Jr. created modern color film in 1935, with three layers of emulsion on one layer of film. They were classical musicians, not chemists, but ended up working with and selling their innovation to Kodak that named the film Kodachrome.