I'm gonna tell you the "problem" as to why Black widow does not have her own movie yet. She's a normal human hero in a world filled with super heroes. In Lucy her character had cool powers but as a master assassin there are no fancy powers and I don't think hand to hand combat alone is gonna satisfy people that much. Don't get me wrong I loved the movie Lucy, but in Marvel she's just a human and nothing more. But I do agree on that there are not enough/any marvel movies with female leads. - By human you mean like Batman?
13 minutes ago