Is it possible that those top 1-2 people just knew so much more than you, going into the class, and had such a strong foundation in closely related material, that they picked it up more quickly? I mean, if the scenario was "my twin brother and I went into a math class with the same level of math knowledge, and he didn't study and got an A, while I studied 15-20 hr/wk and got a B" then I would find that much stronger evidence to conclude that these differences may be innate. But to me it seems likely that the 1-2 people who vastly outperformed everyone else may have just been setting themselves up to do that for the previous 10 years. By which I mean, they were intensively studying math throughout high school (and likely before), so that although they may not have known the course material going in, after seeing it once they think, "oh, yes, that's an obvious result based on x, y, z things that I already know. And it's a very nice way of thinking about w." Whereas you, not knowing x, y, z, or w, don't have any of that intuition. So they can make connections and learn by analogy "effortlessly" while you have to study much more to understand these concepts.
Thoughts?