Ironman was a litmus test for Marvel Studios to see if there was an audience for something like the MCU. It did some preliminary work, but the movie could stand alone if it became a one-and-done movie. In that sense, it was a pretty isolated film, as were most of the Phase One films that were about presenting a character, telling a compelling story, and satisfying the audience.
Post Office-avengerbut everything changed. Marvel quickly changed gears, no longer content to just tell stories on the big screen. First came Agents of S.H.I.E.L.D., a television program that was consistent with the continuity of the MCU and explored the implications of MCU The winter soldier, civil warand other big-screen flicks. Then the Netflix series came out, giving Marvel a finer outlet on the small screen that was still perfectly interwoven with the timeline of the movies. Before anyone knew, Marvel had successfully made his cinematic universe a hybrid that encapsulated not just movies but television as well.
Marvel's world spanned all sorts of screens, each trailing the canon of the film for a truly integrated universe, constantly referencing events that ran in completely different IPs. Now we have over twenty big budget blockbusters and numerous TV shows on many different networks, all working to tell their own story of the bigger Marvel story. What started as the only science fiction film has evolved into an unprecedented experience in the world of screen storytelling.