That's why I said head canon.

Head canon is where you make shit up for internal entertainment. This being on lemmy, I kinda assumed that even in a science meme community, head canon would be understood. Sorry about that ¯\_(ツ)_/¯

I'm dubious if pansexual being invented by people that didn't understand that though. The word pansexual is usually acknowledged as being derived from pansexualism, which was coined whole by or about Freud (supposedly, I wasn't alive then to know) to mean that sex and sexuality are a primary motivation in all human existence.

The later term came around back in the seventies, and was being used to mean having no limits on sexuality. I've run across people saying they used it as far back as the sixties in that context, but they were dirty hippie potheads, sooo...

In any case, it was in use during at least the late seventies, as it showed up in print in some of the books of the era that were part of the sexual revolution. And it didn't "just" mean trans inclusive, nor was it used as a direct synonym for bisexual. It very much included things like what gets called polyamory now, group activity, etc. The core usage was that the person calling themselves pansexual was not limiting themselves to the standard paradigm, which is a different thing from being attracted to and/or having hetero and/or homo sexual activity.

I'm not sure exactly when the term got shifted to the increasingly common usage of "trans inclusive sexual orientation", though I remember running into it as far back as either the late nineties or early oughts.

So, I'm fairly confident that the people back in the sixties or seventies that originated it as something close to an orientation knew that bisexuality existed, and saw pansexual as being something that went beyond it in some way. I've definitely never run across any definitive "first use" where the term was defined in print. Not saying it wasn't, just that none of my reading of the matter back in the day uncovered it, and human sexuality was very present in my mom's collection of books. Our town library even included books on the subject, though less than what my mom had, and way less than I had access to later on.

With that in mind, if you have run across something definitive regarding the origin of the term either in the seventies sense, or its adoption as trans inclusive, I would absolutely love it if you could guide me to it. Not being snarky, not being contrarian, I'd genuinely enjoy learning more about it because it's a subject that's fascinated me since I was old enough to think about sex at all.