Originally Posted by marcvader
Sasquatch, Black Knight, Guardian, Cloak, Dagger, Shroud, etc
The difference is that Captain Marvel had his own title, while the ones you mention don't. Younger generations don't know much about Captain Marvel, because he belonged to the 60s and 70s, but he was considered a major character in the Marvel roster back then. Marvel has tried unsuccessfully to revive interest in him in subsequent decades with variant Captains like Genis-Vell and Photon, and even Mar-Vell revisited.
All that adds up to him being a lot more than a D-lister.