Vladimir, it's good to see you in the contest and I congratulate you on a clear and well illustrated essay.
You say that if the message we perceive is distorted then we cannot assume we have the correct answer. To some extent yes but eventually as more information is gathered our certainty increases.
For example, in your elephant picture the blind observers must have been unlucky to find things in just the right places to make it seem like they were touching an elephant. If they carry on they would soon find that the parts do not join up. We can never be absolutely certain but we can increase our certainty to a higher degree. Isn't that good enough?
In Einstein's original formulation of relativity the observer played a role, but when Minkowski reformulated it as geometry the observer was no longer needed. People have tried to reinterpret quantum mechanics to get ird of the observer but without success, yet the world was here before any observers. Was that history an illusion of the observer?