Aren't Dragons considered a race? They are of mundus, and unlike the various beasts that share the realm, they have an unprecedented amount of 'higher' valued aspects that make them akin to being totally unrelated to beasts. Their self-awareness and their higher modes of thinking are but a few examples.
They are highly intelligent, have their own language (both written and spoken) and have an inclination toward magic. They even seem to have their own culture (of a sort) in that involves the idea of 'truth' being the supreme power. To them, the dominating thuum is the equivalence of being 'right' seeing as how a battle between dragons is actually a debate.
Combined with the fact that they ruled over mortals (particularly the nords) with their own system of governance that was highly domineering, I would think dragon should be considered a race on its own. A race that could be considered the "strongest" in various terms.
Their brute strength alone is at least 10 times the strength of any nord or redguard, have an innate sense of magic that can surpass any magic thrown by an altmer or breton, and had their own society that seemed beyond or parallel to any other society held at the time.
(But of course, even despite this, I suppose dragons could be considered more along the lines of 'creatures' rather than a 'race'. But that seems highly demeaning considering their higher thought processes.)