Jan Vern is an agent with the IPI.
That stands for Interplanetary Investigations. The name sounds like it would be a private detective business but the scope of the authority that is demonstated in the two recorded adventures that we have would indicate a governmental agency.
We know that the time frame for the action is the future, likely at least several centuries. Earth still appears to be a center point but The variety of humanoids encountered by Vern is impressive; all with the traditional body parts but after that the differences are wide. Green skin, orange skin, red skin, brown skin - all represented. Some have reptilian features while others go even a bit more extreme. This all shows that the reach for the Earthlings have extended far enough to have encountered beings from other planets and they have formed a unified government. How many different worlds are involved is not mentioned but is likely to be a good number; many of these are in our solar system as we meet those from Jupiter and Pluto, to mention two.
Vern is an Earthling, white-skinned with short blond hair. He is fairly tall, slender and obviously in good physical shape. Unless undercover, Vern is typically dressed in what would appear to be a standard IPI uniform - blue jumpsuit with a wide v-collar, white belt, and high white boots.
As would be expected for a series of adventures taking place in the future, Vern is equipped with an assortment of cool gadgets and devices including ray guns which allow for impressive, non-lethal curtailment of individuals - i.e., opponents get zapped but not killed. Of course, those he goes up against are also able to bring their own neat toys to fight.
We learn virtually nothing about Vern other than he is an agent, has been for some time, and is well respected.