Your counts are way off. There’ve been three Iron Men[sup]1[/sup], four Spider-Men[sup]2[/sup], five Ghost Riders[sup]3[/sup], and a whopping twelve[sup]4[/sup] Captain Americas.
That’s just counting guys from the 616 reality, not alternate dimension versions.
Tony Stark, James Rhodes, Victor Von Doom. I’m not count Riri Williams, as she’s going to go by Iron Heart, not Iron Man, nor any of the characters who have gone under the Rescue hero name.
Peter Parker, Ben Reilly, Otto Octavius, Miles Morales post Secret Wars.
Carter Slade, Johnny Blaze, Danny Ketch, Alejandra Jones, Robbie Reyes.
(Deep breath) Steve Rogers, Isaiah Bradley, William Nasland, Jeffery Mace, William Burnside, Bob Russo, “Scar” Turpin (those last two, for only one issue each), Roscoe Simmons (two issues, before the Red Skull killed him), John Walker, Sam Wilson, Bucky Barnes, and Dave Rickford.