Never been a comic reader and have a question

I'm a big fan of the movies . I also love origin stories but I asked a worker in a comic store if there was a comic that was like a reboot with complete origin stories ? The other question I had was is there a running comic in which Superman is the only superhero in that " universe?" He said no to that as well.
I was surprised. But is this true? I like knowing the history of everything that is " canon" just like I want to see every episode of my favourite tv shows.
I'd enjoy collecting but unfortunately I can't justify the cost if I'm only getting a percentage of the story.

Never been a comic reader and have a question