...But the episode itself doesn't identify the character or his rank. Except perhaps in the end credits, but those aren't part of the Star Trek universe (and we don't really have to think that Kirk was in every episode replaced by an impostor named William Shatner, or that Uhura in fact spelled her name with three u's).
I mean, yeah, writer intention and all that. But we have now seen samples of Starfleet insignia from before and after the TOS pilots, and the system seems unchanged and continuous. Which rather supports the idea that this guy here was a Lt(jg), that Kirk in "Where No Man" was a Commander by rank, and that young Pike, doing a milk run with half a crew, was a mere Lt.