In dutch it is men, in german man (I think in scnadinavia aswell btw) and in french on. All three from the word human (homme in french) It is speculated that the english form is an imitation of the french version, since it does not refer to (hu)man.
Did some research and it seems eräs is close in finnish? Though you never get a good sense of the usage of a word by just reading about it. So I'm probably wrong.