The guys at the top of the heap were heroes. That's how they thought of themselves. And what they wanted to hear about were the exploits of other heroes (preferably ones they counted as ancestors.) Ordinary people barely exist in epic. They are ants, there to make up numbers, and to form a circle so the heroes can duel in the centre.
Carrying this art form over into the modern world is tricky. Society- or at least our view of society- is rather more complex. We don't have heroes the way they had heroes.
Which is why, I think, most epic movies are so unsatisfactory.
Hero (ha ha)- the Chinese epic that came out a couple of years ago- solves the problem by extreme stylisation. This isn't the real past, it's a mythical past. The film accepts the Bronze Age world view and puts it up there on screen without criticism or irony.
Lord of the Rings attempts something similar. If it's less successful it's because Peter Jackson isn't half so good a director as Yimou Zhang.
The average Hollywood epic goes for compromise. There's usually an attempt to insert a hero of Bronze Age forthrightness into a world that is conceived, in modern terms, as being at least moderately complex. In Gladiator, for example, our single-minded military hero chops his way through a corrupt and cruel world towards a confrontation in the arena with the Emperor himself- and I don't believe a frame of it. In societies as complex as Imperial Rome really was there are structures in place to contain and restrict heroism and make sure that pugs with a grudge don't ever get a shot at the main title.
The best epics are those in which the hero is properly integrated into his society. Hero achieves this by giving us a society of heroic simplicity. My pick as best Hollywood epic of all time- El Cid- does it by making the mismatch between the hero and his society the very pivot on which the drama turns. A man who truly believes in the Christian chivalric ideals comes up against a king who only pretends he does. Rodrigo Diaz de Vivar is a misfit, a magnificent lost cause, with a whiff (only a whiff) of quixotic absurdity about him. Heroism, instead of being a given, becomes the thing at issue. It is put on trial and tested and indulged when useful then sent on its way with a tear.