The MCU is literally built on the back of characters no one cared about. Forget Iron Man and Captain America for a second, since most people at least had heard of them.
We got films out of Ant Man, Black Panther, The Guardians of the Galaxy, Dr. Strange, and Captain Marvel. Captain Marvel wasn't just a property no one had heard of, it was a property that had repeatedly failed to get anyone interested in it despite numerous reboots since the 1970s. Carol isn't even the first Captain Marvel, she's something like the 5th or 6th and her books were struggling too before the feature film. Forget "depth of character" this was a character actively loathed by comic fans. Now she's A-list.
We got Luke Cage, Jessica Jones, and an Iron Fist TV show on netflix for multiple seasons each.
We're getting a Black Widow Film, a Hawkeye TV show, a Moon Knight(?!) film, the Eternals, and Shang-Chi.
Saying Black Cat or Morbius "don't have the footprint" for a feature film while Shang Chi and the Eternals do is nonsense. It's about the concept, not name recognition.