man is an old english word for human being
in the old english a male human was called a Wer, or Wæpman, from which we derive such words as Werewolf
a female human was called a Wyf or Wyfman, from which we derive Wife
basically 'man' was and is still is used as gender neutral term for human beings
so when the bible says that God created man in His own image, it is talking about humanity as a whole - both male and female
and for the record… i am annoyed that you didn't eeyore, tigger and pigletting go and google this for yourself