I think the key bit is that "fe-" is not some sort of prefix, but part of a totally different word that had its spelling changed for consistency. This is unlike

I think the key bit is that "fe-" is not some sort of prefix, but part of a totally different word that had its spelling changed for consistency. This is unlike the "wo-" in woman, which in fact a prefix originally meaning "wife". Weirdly, English got "man" from Old German (meaning a person), but "human" from the Latin "homo", so just like female, the "hu-" in human isn't a prefix either, but derived from a totally different word. Then again, "man" extends back to proto-Indo- European, so maybe it's all related regardless.