What is the impact of having gods that are not only real, physical presences, but mortal (if very long-lived) ones? Gods that face certain limitations based on their own physiology and nature? That’s Dragons, at least Elder ones, in this setting.
Dragons are the ultimate predators: bigger, smarter, and more powerful than people will ever be. Dragons don’t even reach maturity until they are a few hundred years old, and they continue growing throughout their lives. Elder Dragons can and do live for thousands of years with the aid of their magic.
And their magic is powerful. The Dragons were the first to master control of the Elements. Moreover, Dragon minds are powerful and flexible enough to comprehend the symbolic languages of multiple elements, more than any one human sorcerer can comprehend.
A world can only sustain a small number of Elder Dragons and not that many more mature Dragons. Once the population reaches a certain critical mass, conflict over scarce resources arises. Such wars, fought between small numbers of powerful magical creature, are very likely to lead to extermination. As Dragons traveled to other worlds, they found repeated evidence of self-inflicted genocide in the archaeological record.
In addition, Dragons by their nature are competitive and solitary creatures. Yet individual Dragons can only accomplish so much, even over the span of millennia. On their own, Dragons can barely sustain or advance a civilization. It took them much longer to develop certain cultural institutions.
In effect, Dragons need the help of lesser beings to fulfill their true potential by sustaining larger populations, waging proxy conflicts, and forming durable societies. In essence, Draconic civilization would not exist without their followers.
The Dragons taught Humans and other lesser beings the secrets of Elemental control and also fostered the study of alchemy. They encouraged the development of many other disciplines and technologies. In a sense, Dragons are capable of treating lesser species as their surrogate offspring, nurturing them in a way that their instincts prevent them from doing with their own biological young.
In addition, the Dragon-Kings and Queens protect their worshippers from the many dangers posed by other supernaturally powerful beings such as the Gods Above or the Dark Ones. (At least that’s how the Dragons present it.)