This is a very broad question as there are many different types of oppression, including racial, class, gender, economic and political. So I will answer this in light of the text The Island of Doctor Moreau, by H.G. Wells. In this story, we discover the diary of Edward Prendick, a man who was shipwrecked, subsequently rescued, and taken aboard a ship named Ipecacuanha. Once aboard, he meets the frequently-drunk Captain Davies and a one-time medical student named Montgomery. Also on board the vessel is a man he refers to as "misshapen" and a host of animals.
Once they reach their destination—a far-flung island—the former medical student, Montgomery, and the animals go ashore. Prendrick wants to stay aboard the ship, but the Captain will not allow it and so forces Pendrick into a small skiff that is pushed out onto the water. Not content to let Pendrick die, Montgomery and a white-haired man rescue Pendrick and bring him ashore. Pendrick later discovers that the white-haired man is Dr. Moreau, who was compelled to leave Great Britain some years ago after his disturbing medical experiments were made public.
When Pendrick discovers that Moreau is performing vivisections on the humans and animals on the island, he is deeply unsettled and tries to escape even as Moreau attempts to convince Pendrick of the importance of his work. In the end, both Moreau and Montgomery end up victims of the very creatures of the 'humanized animals" they created.
In the case of the creatures on the island, they would never have existed at all had it not been for Moreau and his decision to create a sense of disquiet and fear on the island; once he sowed these seeds of distress, he was able to present himself and his dubious pseudo-scientific methods as the answer to these seemingly overwhelming problems that hadn't really existed in the first place.
What bothers Pendrick most about Moreau's experiments is Moreau's flippancy about the pain he causes he subjects and the complete lack of conscience he shows in "playing God." Pendrick believes living in this half-human and half-animal state is the worst curse of all:
Before, they had been beasts, their instincts fitly adapted to their surrounds. Now they stumbled in the shackles of humanity, lived in a fear that never dies, fretted by a law they could not understand; their mock-human existence, begun in agony, was one long internal struggle, one long dread of Moreau—and for what? It was the wantonness of it that stirred me.
I believe that we would have more control over our daily lives and be happier in our choices if we lived in a world in which fear was not the primary factor guiding our decisions. But what's good for individuals is not always what our leaders want. As author Michael Crichton writes:
Social control is best managed through fear.
Oppression gives us little reason to hope. If we were living in a time and place in which fear was not a tool used to oppress, we would likely be more apt to hope, dream, plan for the future, reach out to others and to be more daring in our individual pursuits.