One of my other venures in life, is a Film Festival that i founded and have run for several years in NYC. As such, i can give you some insight into how films get into this festival, and possible others.
The submission checklist:
Yes we could say that you just need to have an amazing film, but that would be very vague now wouldn't it? The truth is, films can all be great in many ways, but we have to be far more specific in who we accept, so here are the main things to look at within your film to see if they will have a high likeliness of being screened:
Image quality: Now granted, we don't care whether it was shot in 4K, 8K, or Standard def! What we do care is that the image isn't out of focus, is overall pleasing to look at, and most importantly does not have elements/motion that reveals to the audience that the camera exists(unless a documentary or intentionally breaking the 4th wall).
Characters/Acting: Are your actor's performances believable, or are they just reading lines? It is very hard for an audience to be emotionally involved in a film where they don't believe the performers are emotionally involved.
Direction: This is how well the movie is paced and how it flows. Generally speaking an action movie will be directed to be fast paced, a drama to have a slower pace. Overall, does the movie feel correct for what its story is?
Editing: Some say there is no final edit, and that's because there are infinite ways to cut a film. At the minimum, ask yourself, do you notice the editing? A well edited film does not appear edited, it simply flows. In a poorly edited film the audience can start to notice the cuts because they don't make visual sense. Again, pacing, and logic. 90% of the time a film can be trimmed, which comes again from asking outsiders opinions.
Sound: This is where we see the most point deductions, because it is often neglected. The sound encompasses several aspects: Dialog, Foley/natural, Effects, Soundtrack. By far the most important for most films is the Dialog, if we can't hear the actors clearly, we can't watch the film. Be sure there is no hissing/popping/noise/etc... to distract from the dialog. If there is, you still can ADR with your actors to fix it. Then make sure the soundtrack and Foley make sense as well.
Story: Above all, this is what will make or break a film, is the story compelling? Does it keep the audience interested? Does it drag? This is where many filmmakers fall short when they do not get external opinions about their films which could help them make the film better. So be sure to get people who are NOT involved in the project and give you their honest opinion!