When I was growing up in the 70's and 80's there was not one kid in my neighborhood who didn't know who Iron Man or Captain America was. They were top tier characters back then. I could not have been imagining it all these years.
Iron Man/Tony Stark also had one of the biggest ground breaking stories back in 1979. Tony's fall into alcoholism. There was also a popular Iron and Cartoon in the 60's and 90's. Maybe not as popular as the x men cartoon. I always thought the X-Men was kinda second tier until later on..... Though that was a preference thing....
That was the 70s. I was born in 84 and really didn't get that attached to it until the animated shows. Before that I was into mostly Teenage Mutant Ninja Turtles, Ghostbusters and Bug Bunny Cartoons (And Tiny Toon Adventures, but I think that was more of an early 90s thing). I guess one can say I came pretty late.