I believe Gus Grissom was the second American to fly in Space which makes him a very big part of the so-called "space race". Anybody that was involved in the space race and actually contributed to it has to be considered a hero, whether they are well known by the wider public or not.
Gus Grissom entered the space race as an early pioneer during the Mercury missions and took all the risks of space flight. He went through many extreme training programs and missions to help establish the first steps into space. He was courageous and daring along with many of the first astronauts.
Yes, Grissom was one of the heroes of the space race, because he was one of the first astronauts to work on the Mercury project. He was trained as an engineer and he was also a pilot. Grissom and the others had vision. They knew what they wanted to accomplish and they set out to do it.
He was one of the original NASA Project Mercury astronauts, a United States Air Force test pilot and a mechanical engineer. He was the second American to fly in space, and the first member of the NASA Astronaut Corps to fly in space twice. He was the first of the Mercury Seven to die. He was also a recipient of the Distinguished Flying Cross and, posthumously, the Congressional Space Medal of Honor.