If they weren't insecure about Cap, then why they didn't give him a more prominent place in Avengers?
And why call him Captain Rogers in TWS? What reason did Cap have for not wanting to continue takin' on the mantle of Captain America, if he was a hero?
And, what about his abilites, is he superhuman or human? Why does seems that at one time he is one human and on another he seems superhuman?
Just because he had a few less minutes than RDJ doesn't mean they're insecure. He actually did have more of a role but it was cut down.
And TWS Nobody was referred to by thier super hero names, not once was Natasha referred to as Black Widow or Wilson as falcon. He was capt.Rogers because he is an agent of shield not a vigilante in the streets like batman or spiderman who has to be referred to as thier super hero names. In Xmen how often is logan referred to as wolverine, not all that often but it doesnt stop him from being wolverine.
It would sound highly unnatural for every one to be running around calling him captain America in every scene, especially since his identity isn't a secret. He works for a government agency but that doesn't make him any less a hero, hell he donned his old suit once it was time to take out shield. Steve Rogers, Captain Rogers, Agent Rogers are all a part of Captain America as a whole.
Are you kidding me, what point has ever just been human? everything he's done since he's got the serum proves other wise:
Tore the door off a car
Running through doors and walls with no problem
Resisted the magnetic pull of the shield hand cuffs
Jumps 15 ft in the air with ease
Jumped out of an elevator over 50 ft off the ground and hit the ground and got up without trouble
Constantly throwing men around with one arm
Lifted a boxing bag and hung it with one arm like it was a sack of laundry
Got shot through the back and was still able to get up and pull a beam that likely weighed a couple tons off of bucky
Tore the arm off a chituari
Got shot by a chituari and got back up to fight
Single handedly took down a jet
Withstood a strike from mjolnir
Either you have no concept of human strength or weren't paying very good attention to these movies lol
And marvel couldn't be too ashamed of cap given how fast they green lit Cap3.