Newton's law of gravity is mathematically identical to Kepler's laws of
planetary motion, which had been published many years before.

What Newton did was provide a simple, concise reason why Kepler's empirical
laws are true; a new way of looking at the problem. Einstein did the same
for dynamics.

Nobody goes around claiming that Newton plagiarised previous scientists when
forming his laws of gravitation.

Only cranks go round claiming that Einstein plagiarised previous scientists
when forming Special Relativity.