Black Widow was in no doubt a great movie, but it felt more like a sequel to a film that was never made. Ideally speaking, Marvel should have released a Black Widow movie as a part of phase 2. This movie would have started with Natasha as a child, how she was recruited and trained by the red room, how she got on S.H.I.E.L.D.'s radar in a bad way ( maybe mention about the hospital fire or Sao Paulo as referenced in Avengers 1) and then ending with her defection to S.H.I.E.L.D. by bombing Dreykov ( and his daughter) in Budapest. Then in phase 3 after Civil War, the black widow movie sequel should have been released. The sequel would have been the film that we all saw right now in 2021. The end credits could have been a part of the Falcon and the Winter Soldier. This way we would have been able to get way more backstory for Natasha Romanoff, instead of an opening montage (which was the best opening montage I have ever seen, which is also why I think expanding on that would have been amazing) and a couple of lines about the events of Budapest.