We can presume, but Nature keeps her own counsel. Anywhere there is any scope for intelligent behavior and capacity to exercise it, we should expect to see nature explore that, sooner or later. I know no reason to think that could not have been done yet.

There is some scope for winged humans, and hypothetically some capacity to exercise it. Nature did not explore this route. The opportunity cost of exploratory settling into a non-preferred niche usually outweighs the benefits of that exploration simply due to the scarcity of available resources to buffer against the opportunity cost.

But, as noted, for this case there is very little in the way of cost.

Nature did, in fact, explore the winged-bipeds body plan to full fruition twice, once in mammals, and did winged quadrupeds before and again in mammals. She is progressing on a another as I write this. And, humans did end up conquering the air without growing wings. Nature isn't picky about methods.