Orcs were imagined as nature corrupted and turned against itself, the ultimate symbol of what the Industrial Age was doing to land and humankind. Healthy, natural farmland was being transformed into dead, toxic cities with factors and poorhouses filled with scuttling, foul, treacherous, violently competitive, conflict-driven creatures afraid of the light and enslaved to their masters, bent on transforming the entire world to serve the unblinking, singular Eye of hate, which has far but depth-less sight and can only destroy.
They are elves corrupted by the Eye. Elves are Tolkien's natural human, in harmony with the world but fading, withdrawing, leaving for the Grey Havens, never to return.
Humans are the midpoint between Elf and Orc, with the free will to become either, and the curse to be both.
Dwarves are honourable but flawed with greed and isolationism. They invite trouble and let dragon's into the house, the ultimate symbol of greed and isolationism. They help forge the rings that enslave the nine human kings who enforce the will of the Eye, cloaked in glamour and dead inside. They nine believe themselves kings, just like our leaders, when they are only shadow salves of the tyrant.
Hobbits represent the least powerful and most unlikely heroes among us.The power of one dedicated individual, able to defeat the Eye through knowledge, cooperation, and self-sacrifice, all powered by love.
Tolkien pictured this leading to the Grey Heavens, a return to th natural and rejection of the industrial, but fear the natural lost forever.
However, it seems he may have caught an unintentional glimpse into the dawning Information Age. The Industrial Age transformed farmland into cities, centralized power and wealth and eroded democracy. The Information Age is democratizing information and thus power. Knowledge and the power of cooperation is making true democracy possible as well as true equality. We are beginning to take the first steps in transforming cities into sustainable farms, an Elf combination if I ever heard one. Our cities and we will take our proper, harmonized, equal part in the ecosystem of nature, perhaps ceasing to fight it and ourselves; purging ourselves of the Eye and its slavery.
Elves and Orcs were made as they were. Only Hobbits, Humans and those with Human blood have true free will. The others were ruled largely by their natures until knowledge set them free.
Humans can chose to transform Middle-earth into the Grey Havens or Mordor, the consuming waste.
The story was fiction but like all true art, the choice and consequences involved are real.