What is the clarification of the polytheists' saying in the Qur’an: "Had Allah willed, we would not have associated [anything with Him], nor would our fathers, nor would we have been forbidden anything"? Is their argument considered a reliance on destiny (qadar)? And how did Adam argue with Moses using destiny (qadar)?

The polytheists' reliance on predestination to justify shirk (idolatry) and deviation is invalid. The consensus among followers of all religions and people of intellect is that using predestination as an excuse for sins and transgressions is unacceptable. The polytheist commits shirk by his own choice, not feeling compelled by anyone. If predestination were a valid argument for sin, it would also be valid for Iblis and Pharaoh. Therefore, everything in existence occurs by God's will and decree, but no one has an excuse through predestination. Rather, God possesses the conclusive argument. And whoever uses predestination to justify committing acts of disobedience, their argument is null and void.