Explain verse 39:6

First Adam was created, then his wife and then people. But why is it said in 39:6 that Allah first created people from one person (Adam) and only then created a woman from Adam? > He created you from one soul. Then He made from it its mate, and He > produced for you from the grazing livestock eight mates. He creates > you in the wombs of your mothers, creation after creation, within > three darknesses. That is Allah, your Lord; to Him belongs dominion. > There is no deity except Him, so how are you averted? (Az-Zumar : > 6) I'm just confused by the word "Then" (summa) here.