Heroes are people who rise above the norm for what is expected if them. So some cops are heros; but all cops aren’t heros — any more than all soldiers, all firemen, all former POW’s, etc.
Yes, it is a job, no more.
Those whom you mention sign up for jobs in which they might need to “Rise above what is expected of them”
Fr George Rutler recounted that on 9/12, he was stopped by firefighters and police officers on their way to the site for the sacrament of Confession. **They knew what they were headed towards and they went anyway.**
Sure, a lot of people sign up for other reasons, but most would be heroes if called upon. The fact that many individuals have not be called upon to do so does not mitigate the fact that they signed up for jobs which quite likely will put their lives in danger, and that in and of itself is rising above the usual.