When were women invented?

Most of the multi-celled Life forms on Earth are based on a binary - a male and a female design for procreation, breeding.

As far as science is concerned, women were never "invented". They have developed right alongside men for as long as human ancestry can be traced.

If you take the religious approach:

Some religions - like the old Nordic/Viking religion - have men and women created (near enough) simultaneously.

Some - like Christianity - claims that men were created first.