the term "amen" likely entered hebrew from the egyptian, where it refers to the hybrid creator-fertility deity, which was also a sun god. this cult was preferred by a specific pharoah, which gave it primacy in the egyptian empire. as such, it became a monotheistic religion in the egyptian cultural region, which canaan was a protectorate and pseudo-colony of. evidence for the existence of an independent jewish religion, or even a substantive independent jewish state, really does not exist until after the captivity, but the language at least traces back through to an egyptian hegemony period, in a canaan that may have had almost no resemblance to the one depicted in the hebrew scriptures, at all. the archaeology suggests that there was a very ancient, stagnant, backwater culture in this region that was transitional between deeply rooted egyptian tradition and the neighbouring phoenecian/carthaginian culture, and which disappeared around the period of assyrian and babylonian hegemony, only to be reconstructed in deeply altered form during the persian period. further, it seems that any memory of this was eliminated during the purge of history that occurred following the carthaginian genocide, leaving the (largely unreliable) hebrew scriptures as the only remaining historical source. and, perhaps they were spared destruction precisely due to their unreliability.
amen was a virile, hyper-masculine deity. a gender inclusive addition would have been to say "amen, and amunet".