The world is ruled by three people each over their own group. A vampire rules the supernatural creatures. A sorceress rules over all magic users. And a man, granted a great man, rules over all humans. But the man is feeling a bit inadequate.
His humans are ordinary. They work, they provide for their family, they do all the normal things we do in our current life. They are not treated badly by the others, they just aren't special like the other groups. Their technology doesn't really set them apart as the other two groups have a hand it in.
Besides just being food, target practice or worker bees, in a modern day world where magic is ordinary and supernatural creatures walk among us, how can humans prove they're just as good if not better than the other groups?
A little more clarification: Magic is hereditary, you can only be born with magical abilities, but in addition to that, you do need to be taught to be able to control it properly. Magic users can mate with normal humans sometimes producing a child with magical abilities. Supernaturals are the traditional western varieties, vampire, werewolf, fairie, ghosts, etc. acting and reproducing in the traditional ways, i.e. vampires and werewolves create more through their bites, fairies mate with other fairies, ghosts are dead, etc. Interspecies relationships are not frowned upon.
The world is current day, only slightly more advanced technology wise. Everyone has been out in the open for centuries. Magic allows for better healing and some conveniences, but of course not everyone can use it or have access to it. The world is (mostly) at peace as any time fighting breaks out one or the other steps in to stop it.