Moses warned the Jewish people, "Take care lest you say to yourself, 'It is my own strength and the might of my hand that I have accumulated this wealth for me."
Children often surpass their parents in many ways, even though they inherit their talents and abilities from their parents. The reason that children can manifest capabilities their parents do not seem to possess is because these talents remained dormant in the parents and only became active in their children.
Similarly, G-d calls the Jewish people His "children." He has indeed left it up to us to bring the world to its completion, granting us a measure of power the He has relinquished. Thus, when we accomplish something that helps bring the world closer to its ultimate fulfillment, we might mistakenly ascribe this accomplishment to our own power.
Therefore, the Torah reminds us that just as children owe their superior powers to their parents, from whom they inherited them, so do we all owe all our powers to accomplish great things in this world exclusively to G-d.