Unfortunately, you do not understand the issues at hand, but I will summarize:

Newtonian Gravity has several problems:

1. Instaneous action at a distance which even Newton objected to but did not understand how to get around. No finite speed of gravity is logically consistent with reality because it does NOT permit stable orbits.
2. Orbit of Mercury matches Relativity but NOT Newtonian Gravity.
3. Bending of starlight also does not match Newton.
4. No explanation of equality of gravitational and inertial mass which Einstein and NOT Newton explained.
5. No explanation of stellar evolution and mass limits on stars of various types.

The above does not prove that Einstein was correct and Newton was wrong, but rather that Einstein's Theory agreed with observations BETTER than Newton's. In Science, this is how a theory supersedes another. Surely, Einstein's Theory is NOT the ultimate theory of gravity, but it does not need to be to overtake Newton's. Better agreement with observations is all it takes.