JiffyPopTart
Bree-Yark
Are there not 2 MCU Spiderman films? I haven't even seen the second one and I know the villain is Mysterio...because Mysterio is a recognizable villain with a schtick.The MCU movies have been more successful than the X-Men and Spiderman movies. The role of the villain in the MCU is to be punched by the hero.
You probably want to look at Batman movies if you want superhero movies about villains (and where the hero is a shadowy cypher).
I have seen Avengers all the way through multiple times and bits and pieces a million times and couldn't tell you what the bad guys names were.
You don't have to make your movie about the villain to have a good villain. Killmonger was a good villain...plenty of screentime, an understandable goal, and interesting character interaction with the hero. Same with Loki, or Ultron, or even Ghost. For each one of these, though, you have 3 "guy in pale makeup who wants to kill everyone because he is mad" villains nobody remembers.