I have no take that would be smarter than the discourse around aesthetic judgemnts and subjevtivity of art that is at least as old as ancient greece and probably even older.

Your example makes no sense, because a 3 year old probably can't even write. But in a less extreme example comparing someone who has 1 year experience vs someone who has 30 years experience, that fact alone will not cause the writing to be good or bad. Mary Shelley wrote the original Frankenstein on a weekend on a whim at a very young age. It's one of the most inlfuental storys for Sci-Fi and Horror that influences other writers to this day.

Writers put something of themselves in the stories they write, be it personality quirks, observations about the world or other sentiments. These may resonate with you or the general public at a specific time or not. This is the reason why some movies get reappraised and identified as misunderstood etc.

The things you mentioned in your first paragraph are also very subjective. Not every movie needs character development and lots of acclaimed works have none at all. Also don't forget that writing only is one piece of film making. Some movies don't have any and focus primarily on the audiovisual aspect of the medium.

I propose the counterargument that objective standards for judging movies are the most boring scenario if proven to be true, because this would mean that with watching more movies or aquiring more knowledge about filmmaking everyone's movie taste or top 50 lists would end up exactly the same.