Iron Man was released by the original studio, which had the film rights.
Marvel Studios took the character back for a very silly reason.
Iron Man is a B-list character that launched him into mainstream popularity.
He also started the successful cinematic universe that continues to run today with several films per year and streaming series.
Iron Man could have made the MCU a reality if it weren't for him.
However, Marvel Studios didn’t own the rights to Iron Man at the time they began to produce their own films.
Iron Man was developed at New Line Cinema for years.
This studio had previously produced successful series such as A Nightmare on Elm Street and the live-action Teenage Mutant Ninja Turtles Trilogy,
the Blade trilogy, the Lord of the Rings trilogy, and the Teenage Mutant Ninja Turtles trilogy.