Five Marvel Cinematic Universe TV Shows that Could Take Place Pre-WWII
Captain America: The First Avenger, and the television series "Agent Carter" took place mostly in the 1940's, but besides those two properties, every Marvel production has taken place almost entirely in "present day" (besides for sporadic flashbacks).
Isn't weird that there has been little explanation of why, all of a sudden, the world is filled with superheroes all at the same time. At the end of the first Iron Man movie, Nick Fury says "so you think you're the only superhero?" One way to explain the seeming absence of others with extraordinary powers is have the present day characters think of them as legends. Another explanation is that the characters were successful in staying off the general public's radar.
Legend of the Ghost Rider
In May of 2013, the film rights to "Ghost Rider" reverted from Sony to Marvel. Though the "Ghost Rider" films starring Nicholas Cage took place in present day, a potential television series could take place at any time, due to the fact that the mantle has been passed down over many years.
Marvel Television is currently using one incarnation of the character, Robbie Reyes. Another, earlier Ghost Rider could provide more insight into the origin of the mantle.
Kid Colt/Two-Gun Kid
Kid Colt and the Two-Gun Kid are Marvel characters that originated in the wild west. Either of these characters could support a television show, and either could be featured in the other's show.
Kid Colt was even briefly alluded to as being a real person in the second season of the television show, Agent Carter.
The character "Dracula" is old enough that it is now available for use by anyone, without legal repercussions, as it is a public domain character. Marvel has used many of these types of characters in their comic books, such as Thor, Hercules, and Merlin (among many others) who are all public domain characters.
Such a show could eventually link back up with other potential Marvel vampire projects, such as a possible "Blade" Netflix series.
The Ravagers were featured in the 2014 Marvel hit, Guardians of the Galaxy. They are essentially a group of space-bandits. They have been operating as early as the 1980's, as demonstrated by the opening scene of Guardians of the Galaxy.
A potential television series could feature a young Yondu (we have no idea how long his species ages), as well as young versions of other characters from the movie. Not only would this help flesh out other periods of time in the MCU, but it could flesh out unchartered galaxies.
The Legend of the Black Panther
As T'Challa says in Captain America: Civil War, the mantle of the Black Panther has been passed down from generation to generation. A potential television show could take place in essentially any time period.
I think the original discovery of vibranium, and the immediate ramifications of discovering such a powerful metal would have on a country, would be interesting to develop. Building such an advanced, yet secret nation, would be immensely interesting.