I think the reason Neil Armstrong is considered a hero is because he took the greatest personal risk on the moon mission, or at least he was the first to do it (Buzz Aldrin took the same risk, of course). There are undoubtedly numerous scientists and engineers who contributed as much and probably more to the moon missions. But they did not incur much, if any, personal risk. Somebody had to take that risk, and Neil Armstrong was the first to do it.