There is no other way to put this: essentially everything about Popular Consciousness Kirk is bullshit. Kirk, as received through mass culture memory and reflected in its productive imaginary (and subsequent franchise output, including the reboot movies), has little or no basis in Shatner's performance and the television show as aired. Macho, brash Kirk is a mass hallucination.
I'm going to walk through this because it's important for ST:TOS's reception, but more importantly because I believe people often rewatch the text or even watch it afresh and cannot see what they are watching through the haze of bullshit that is the received idea of what they're seeing. You "know" Star Trek before you ever see Star Trek: a 'naive' encounter with such a culturally cathected text is almost impossible, and even if you manage it you probably also have strong ideas about that period of history, era of SF, style of television, etc to contend with.