Re: Starfleet Starship Insignia was all supposed to be the same?
I suspect that that secretary or whatever with the arrowhead in "The Menagerie" was just a costuming blunder that fell through the cracks, and even if someone along the line caught it, it wasn't considered important enough to fix and/or they decided no viewer would notice or care.
“A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP” — Leonard Nimoy (1931-2015)