At this time Adam was all alone on the earth with only birds and fish to talk to so God made all the land animals after he said this. After none of the animals made a suitable companion God made woman and saw that she was good :) (genesis 1 in a nut shell)
Because He didn't think man should be alone. Everything else He made, He thought it was GOOD! But He thought that man being alone was NOT GOOD, so he made Eve, from Adam's rib! And He saw that it was GOOD! Amen!
He had already created each higher animal with helpers even certain plants. In fact in the case of flower it appears the pistil (female) was made first and Anthers (male in fact numerous in most cases per female) was made last.