Iron Man is neither Marvel’s #1 character nor their mascot.
It’s still Spider-Man.
Iron Man is the centerpiece of the MCU but he’s never outsold Spider-Man once since 2008.
Spider-Man generates more news stories than Iron Man in nerd and popular press.
Spider-Man has had 10 TV shows where he is the main or central character, 3 of which have aired since 2008. Iron Man has only been a central character in 8 TV shows in his entire existence and in 6 of those he wasn’t even the main/central character
Spider-Man merchandise outsells all Iron Man and Batman merch COMBINED.
I feel like the MCU’s take on Spider-Man gets worse in every movie. He was great in Civil War because even though he was a fanboy, he was still very much his own character and has as much agency as the rest of the heroes. He even threatens Tony Stark at one point. After that movie however, he’s slowly regressed into being nothing more than Tony Stark’s sidekick. His so-called “arc” in Homecoming is completely undone by Infinity War when he straight up becomes Iron Man’s sidekick. The Iron Spider suit robs his character of any impact because instead of going “Spider-Man is cool” you’re going “that suit is cool!”. He doesn’t even need it, it’s not helping him breathe in space or anything (mask is constantly off). He also doesn’t say or contribute anything useful unless Tony tells him to (“Aliens” plan for example).