How are we to understand that Allah created humans to populate the earth, when Adam would not have descended to the earth had it not been for his wife’s disobedience?

Allah created Adam to be a vicegerent on Earth, and Allah destined his descent to Earth before his creation. He made his disobedience, along with Eve, by eating from the tree, the reason for that descent and a lesson for their progeny. It is not correct to say that Adam would not have descended to Earth had he not eaten from the tree, for Allah could have destined his descent for another reason. Moreover, the disobedience was from both of them, not from Eve alone, and Eve's enticing Adam was a cause of it.