Whenever important physicists are discussed, galileo galilei, isaac newton, and albert einstein seem get the most attention. however, as you’ve seen, galileo formulated or refined many of his discoveries and theories based on the findings of others who came before him, including aristotle and nicolaus copernicus. likewise, newton claimed that he “stood on the shoulders of giants” in developing his work. you’ve just begun your study of physics, but from what you know (or can research and find out) take a position that galileo, newton, and einstein deserve this special recognition. alternately, identify a physicist that you think has been overlooked, compared to these three. do some research and support your opinion with credible arguments

I'm sorry, but I don't think this question can really be answered by anyone but yourself. I would say, if you'd like some direction as to where to start, I have these suggestions:

For Galileo, I would start by researching into his experiments with gravity. Prior to him, among others, objects were thought to behave based purely on mass. He did an experiment atop the leaning tower of pisa to disprove this.

For Newton, look into how his application of calculus and formulation of the laws of motion helped to refine and complete Kepler's laws of motion.

For Einstein, look into special and general relativity, and the existence of space-time and space curvature.

For someone less recognized that might deserve more credit than they do, I would recommend Eratosthenes.

I hope this helps; happy hunting!