"Wer" comes from a PIE root for man (male person), which is the same that led to "vir" being "man" in Latin, hence words like "virile" in English. "Man" is a Germanic root for person, and it can still be seen in modern German, where it's used like "one" in English:

"Man kann nicht immer gewinnen", lit. "one can not always win", fig. "you win some, you lose some".

Over time "man" came to replace "wer" in English for human male. "Wif", original English for "woman", evolved into "wife", sensibly, and woman derived from a hybrid of those two: wif + man, "female person". Wifman -> wiman -> women.

It's not uncommon across languages that there will be one word for both man and husband, or woman and wife. In Latin, vir meant not only man but also husband (in context, obviously). In Spanish, "mi mujer", literally "my woman", is a totally correct way of saying "my wife", with no implication of sexism whatsoever.