Sometimes it is the smallest act that defines someone as a hero. A copper placed in the hand of a street urchin, ignoring a violated law when humanity trumps justice or helping peasants evade an onerous tax are all heroic, but not on the scale of most fantasy novels or role-playing campaigns.
Characters in RPGs are HEROES, not just heroes. Anything they touch affects the entire world, the future of humanity or threatens to end time. No major event occurs without the PCs direct intervention and the villains actively seek the PCs destruction. Even worse, the PCs have a high destiny, born to wage battle against a Dark One/Devil/Cosmic Evilness/Foul Overlord/etc. The PCs matter in a way that no common man understands. Thousands of lives or entire nations teeter on oblivion, held back only by the PCs sheer will and force of arms.
This is the cliché and it is popular because it is a fun experience. PCs have lots of power and their actions have direct, widespread consequences. They can say, “I literally saved the world.”
Sadly, most people simply do not matter. On an individual level, yes, every person is important. In the scope of history though, only a very few exceptional people rise to the level of legend. That said, there is a potential for heroism even in the most humble circumstances.
Rather than build a world-shaking campaign, build a smaller world, but with more humanity. My thought is a simple village threatened by forces beyond their comprehension. Great powers play games of state with vast armies and powerful magics, with the PCs village caught in between. The village has no strategic value, it is literally in the wrong place at the wrong time. Let the campaign revolve around preserving their way of life. Some ideas for adventures include leading scouting parties away from the village, negotiating with one or both sides of the conflict to gain some advantage or simply surviving the aftermath of a magical WMD. The PCs do not have direct control over the larger events and merely fight for survival.
The advantage to this “smaller” approach to a role-playing campaign is the chance to make failure more personal. When epic heroes lose a battle, thousands die and the heroes retreat to plan the next attack. There are more important things to worry about than a few thousand soldiers. The world is at stake! Much as I loathe Stalin, he was right, “One death is a tragedy, a million is statistic.”
Giving the PCs a smaller “life,” makes even one death matter. For extra pathos, have the PCs create spouses. Most adventurers are single because of their lifestyle, so a hearth and home to protect is an unusual situation for most players. Add in some interesting and potentially adversarial NPC villagers (the cowardly, quisling mayor is a personal favorite) and you have all the makings of a great campaign.
I hope this inspired you to try a smaller campaign world. Remember, just because you cannot fight for the entire world does not make fighting for your part of it any less heroic.
Trask, The Last Tyromancer