In most cases a film is a script idea made into filmic reality. I think it is one of the most quintessential part of filmmaking. In most cases we can’t make a film by having no script. I mean we can entirely make a film without a script but it would be hard to do a film with narrative elements without having a narrative in the first place. A script evolves from an idea that has been fleshed out. From what I understand, a script could be one of the most important factors in deciding whether a film will suck, or will be totally awesome. If the screenwriter puts too much or too little information in a script and the director brings everything to life on screen, it will be definitely shown on screen.
If I can’t do justice to my story idea, I’ll try to do justice to other people’s ideas!