Radak: After finishing [to tell] the Chesed that Hashem does with man, and the ability (authority) that He gave to him over all [other creations] - even though man is small and disgraced compared to the great creations above, and he has intellect like them - David returns to thank Hashem.

Malbim: It teaches unlike the philosophers (after refuting their idea that the primary creation is Shamayim).