Whatever Einstein's sources, he should probably be credited with having brought together numerous "lose ends" and made sense of them. I think he would have to number among those who brought physics into the 20th century.
I doubt that Einstein, or any of those who might be credited with "his" ideas, care much about those questions now.
Perhaps a more positive approach would be to ask who the "giants" of 21st century physics bight be.

There never was nothing.