why did god create women?

Genesis 2:18 can answer your question.

For the continuation of the species.  Duh.

Reproduction purposes, just like man's ability to fertilize. 

because humanity could not exist without them.

Because he needed a species, silly.

God created Eve to be a compliment to Adam. So that a man could have a wife who would be their life long partner, mate and companion. To help men populate the earth, raise and care for a family. And women are a gift from God and should be loved and appreciated by their husbands. Women have abilities that men do not have and these are needed for the success of the family. But love and respect is a two way street. These are things that both men and women should have, and give to each other. 

To give you, personally, one more thing to ignore and frustrate you.

Oh, and also Miguel is a blithering idiot. Hope that helps!

It was woman and singular.

Adam had too many ribs and god was keen about recycling.

To give us something to look at on our phones.