Why did God not create more than one wife for Adam, despite the need for procreation, and does this indicate that polygyny is not natural?

The 'proof' (hujjah) in Islamic law is Allah's commands and prohibitions brought by the Prophet (peace be upon him). Turning away from the clear rulings of the Qur'an and Sunnah is not the way of the believers. It is not permissible to oppose Islamic law with divine decree; rather, obedience to the Messengers in what they commanded is obligatory.

Allah the Almighty granted Adam (peace be upon him) one wife, while other prophets had multiple wives. In this, Allah has profound wisdom and overriding benefit. For each, Allah has appointed a law and a clear way. Laws may differ between abrogating and abrogated rulings. Perhaps the wisdom in granting Adam only one wife is that all humanity originates from a single source (father and mother), so that they may show compassion and tenderness towards one another.