The poster for Captain America First Avenger
Movies - TV
Chris Evans Set One Rule Captain America Always Had To Follow
By ERIC VESPE
When Chris Evans was cast as Captain America in "Captain America: The First Avenger," he made a specific request about how Steve Rogers was to be played.
Evans insisted that the only way Rogers works is if he was 100% earnest. Not only that, but he had to have been that way from the very beginning.
This was because Evans truly understood that Steve Rogers was Captain America long before he took the Super Soldier Serum, and wanted to underline that point in his origin story.
In a 2021 interview with Yahoo, screenwriter Christopher Markus noted that Evans was "very conscious of not wanting snark" and had a "very good understanding of Captain America."
It's also possible that Evans wanted to differentiate Rogers from his previous comic book roles, like in the comic "The Losers," where he was another jokester smart aleck.