So far we’ve had an announcement for Black Panther, who is played by a black actor, to have a solo movie. Also, Netflix is having exclusive Originals for four Marvel heroes. One being Luke Cage who is a black character and will be played by a black actor.
Let us not forget Agent Melinda May and Agent Skye, who both are played by actresses of Chinese decent. Scorch is played by a Chinese actor.
Hogun and Howling Commando Jim Morita are both played by Japanese actors. The Collector and Jasper Sitwell, both played by Hispanic actors.
And then Nick Fury, James Rhodes, Heimdall, SHEILD Agent Antonie Triplett, SHIELD Agent Alphonso Mackenzie, Gamora, Sam Wilson, Howling Commando Gabe Jones, Mike Peterson, and Akela Amador are all played by black actors and actresses.
So yes, Marvel is diverse. While these characters are not major characters, they are still very important to the universe of Marvel and to the main characters.