This falls under the "curse of dimensionality"[0]. There are so many tasks/patterns/parts of life that humans can develop specialized skills in that most humans (nearly every human?) are exceptional at something. It might be "identifying the best cardboard scraps and arranging it to make a bed on the sidewalk which is optimally comfortable", or "knowing how to make one specific family member smile" but it'll be something.
If you were to enumerate every skill that improves the life of at least one human, there are probably more than 10 billion such skills which require complex analysis, deep experience, and aptitude to execute at a high level. That's enough for everyone to have something they're "best" at.
One of my favorite quotes is: "If you judge a dolphin by its ability to fly, you are the idiot."
If you're speaking of "generalized intelligence", i.e. some metric which collapses the dimensionality to just a few axes, then obviously you start seeing a more classic distribution where many people are "dumber" than you. But you'd still lack many, many life skills necessary to comfortably take over their life were you to magically swap places with them.
This is trivializing exceptional skill dimensions and exceptional achievements by equating them to the mundane and unremarkable ones.
The curse of dimensionality doesn't imply all skills are equal, only that finding meaningful exceptions in high dimensional data by just data analysis is hard, but we as a society don't find and filter for exceptionality in a data driven way like that, we have a very limited set of dimensions we assign to "success" (financial means being a big one). Someone making a great cardboard bed on the street will never be one of those dimensions.
Undecided. Society is not doing a good job of teasing talent out of people. The only exceptional thing is that some talent is exposed at all...despite our best efforts to stifle it.
“I am, somehow, less interested in the weight and convolutions of Einstein’s brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops.”
― Stephen Jay Gould, The Panda's Thumb: More Reflections in Natural History
Given the curse of dimensionality, I actually think most humans could be exceptional at something--just that something might be incredibly specific, like "washing dishes while hopping on one foot and having fifteen people tickle you with feathers."
Neither of you really have a conclusion. Your modality is overly-reductionist. His is overly broad. In both cases it's impossible to reliably measure. What had ought to reasonably be concluded, then, is that we're entirely ignorant as the the capacities of an individual. From that agnosticism, then, we can build a framework of expectations. And that is entirely elective - if you want to say that nobody is exceptional, you'll seek to reinforce that. If one elects to search in every individual for some special capacity, that's what they'll find. I don't know about you, but between those two framings I'd prefer the latter.
Then there's the objectivist train wherein no expectations are allowed, one must duly profess their ignorance and make baseless measurements in estimation and comment on the distribution of faculties per individual and the degree of resolution to which these measurements are allowed to take place - and it isn't to the degree which any great conclusions can be drawn, I assure you. There is no means by which you can splay out a person's whole and examine them. Time spent with one or two is time spent neglecting some other specimen. Not to mention the interference added by environment. And even in the best of cases that time spent may only be revelatory of some minute fraction of the whole, where again only some shallow conclusions may be drawn and they're only conclusive insofar as the observer has decided they are at some point in the context of time and space within their ever-evolvong system because there's hardly a tape measure suited to the infinite degrees of freedom that exist in the world.
liberals talking about billionaires always gives me a brain aneurysm, but regardless I'd just like to point out that whatever talent and intelligence Musk possesses in your minds, is very inconsequential in comparison to his families wealth through ownership of an emerald mine in apartheid South Africa.
Most people are average, many are below average.