By "normal guy" I mean "Normal Senior NCO Combat Arms Specialist" as opposed to like a self aggrandizing SEAL or a super motto oorah Ranger... or like Master Sergeant Johnson, a larger than life stereotypical drill instructor from Georgia.
In Halo 1, Master Chief is just a pretty normal guy, a bit sarcastic, and has a deep voice. A lot of his lines come off a bit "himbo-ish". His character grows as the series progresses to be a bit more slick and a bit more stoic, a bit less of a himbo and more of a wizened warrior