Relativity is a description of the geometry of the universe. If you would rather believe in your own personal fantasies instead of one of the most well-supported theories in science, congratulations, you are yet another variety of religious loon.
I don't quite agree. There's a mistake in your viewpoint, I think, which is to assume that the progress of science consist in the development of a final theory which bears no modification, and then people disproving that theory because it's wrong, and using evidence to develop the correct theory which also bears no modification, and then you're done. Like, well... we've developed relativity, and that's working really well, so there's nothing else to do there.
It's a very common idea, but it's not quite how things have traditionally worked. People talk about "the theory of evolution" and "the theory of relativity", but in reality there are a lot of sub-theories which continue to develop. We know that somehow life forms evolve and change, and Darwin had a theory about exactly how that happened, and there have been many additions and modifications since that time. We now have a set of currently accepted theories about how various mechanisms in evolution work, and many of those may well be shown to be false, and many more may need modification. But more than that, sometimes there are other ways of looking at things which result in subtly different theories, which are neither quite "true" or "false", but just different ways of looking at things. You can look at a person as an individual organism, or you can look at it as a colony of cells, or you can look at it as a component of a "pack" or a "gene pool". These are all modifications and sub-theories of "evolution". And this is why I object when people argue with creationists by claiming that "the theory of evolution has been proven to be true, and there's no more arguing to be done." No, that's not quite right. We can say with a very high level of certainty that life began as simple forms a very long time ago and evolved to provide the diversity and complexity that we see today, but the exact path and timing is still disputable, and the theory for exactly how that happened is constantly being revised. The exact scientific "theory of evolution" is not set in stone, but the overall concept of evolution is undoubtedly true.
Now that may seem like a tangent, and I'm sorry for that, but I found it easier to describe the idea using evolution rather than physics. It's important, though, since the theory of General Relativity is similar. When Newton developed his theories about the motion of celestial bodies, people saw how clearly this lined up with what we see, and said, "Yes, this is obviously true. No doubting it." And essentially, Newton was right. Unless you have read prior writings on the subject, it might be difficult to understand just how groundbreaking his ideas were, but now we take his physics for granted because they're so fundamental to our current understanding of the world. However, in the time since his work, we've found that his model of the universe doesn't quite work. Einstein seized on one of the ways that it doesn't work, and he made some major changes in the way we view space and time. Those changes, again, made us say, "Yes, this is obviously true. No doubting it." because of how clearly they lined up with the discrepancies with Newton's theories, but ultimately the discrepancies are so mild that we rarely calculate things using Einstein's work. It overturned our Newtonian theory about how and why things work the way that they do, but it didn't quite overturn Newton's work. Most of Newtonian physics still work under most of the circumstances we encounter, and we only bother with relativity when dealing with specialized circumstances.
And so the same might happen with Einstein's work. Someone might pick apart some discrepancy and provide a different explanation for time and space in a way that allows Newton's and Einstein's work to continue under a new umbrella which incorporates new ideas. I can't imagine what that would be, but I couldn't have imagined Einstein's work before I read it. I'm sure people a few hundred years before Newton couldn't have imagined his work.
Now, having said all that, I do agree that there's a distinction between saying "flight is impossible" in 1850 and saying "faster-than-light travel is impossible" today. In 1850, people knew that flight was possible. There were birds and bats who did it, so obviously it was possible. People didn't understand how they did it, so they didn't see any way that we could make flight possible for people (ignoring hot air balloons for the moment). However, our current understanding of physics says that FTL travel simply isn't possible. It's not like we have birds that sometimes travel faster than light, where we can say, "Maybe if we can just figure out what they do..."