Our athletic potential is based largely on the biological traits humans acquired in evolutionary time, while our athletic horizons are mostly built around our experience of the athletic feats of people in our society. We are not in a position to make judgments about our own athletic potential.
Daniel Lieberman, the chief proponent of the endurance running hypothesis, has continually fielded criticisms that humans could not have evolved as endurance runners, because the cognitive burdens of persistence hunting, such as the need for tracking, would have been too great for early hominids to bear (among other things).
In a 2007 paper, Lieberman et. al. respond to such criticisms suggesting that (among other things), “less-encephalized mammals than humans”—i.e. those with smaller brains—are quite capable trackers, etc. Throughout the paper, the authors suggest that such criticisms come from the observation of modern hunter-gatherer groups, such as the Bushmen. They point out that spears and other hunting techniques are relatively recent inventions (from the early stone age), which fundamentally altered the ways in which humans hunted and scavenged.