Do all minor matters, such as the falling of tree leaves, the purchase of animals, the effect of a knife in cutting, in addition to thanking people, fall under Allah's divine decree (Qadaa' and Qadar)?

Everything that happens in the universe, be it small or large, is by Allah's divine decree and destiny (Qada' and Qadar (definition)), as indicated by texts from the Quran and Sunnah (definition), such as His saying, the Almighty: "Indeed, everything We created by [definite] measure" and "And He created everything and determined it with [precise] determination." Allah wrote the destinies of creations fifty thousand years before He created the heavens and the earth. Thus, everything is by [divine] measure, even helplessness and cleverness. This includes the falling of leaves and the purchasing of things; all of that is decreed and written in the Preserved Tablet, for His saying, the Almighty: "And with Him are the keys of the unseen; none knows them except Him. And He knows what is on the land and in the sea. Not a leaf falls but that He knows it. And no grain is there within the darknesses of the earth or [anything] fresh or dry but that it is in a clear register."