Two elements vital to telling a good story are character and setting. A story must be grounded in place and time, and it must center on interesting and relatable people.
On film, the setting is not abstract. Like in the real world, the setting is what you actually see around the characters - that is, it is where the characters are located. The "art" team designs and manipulates this backdrop, whether they use a natural location or build a studio set. They use color, lighting, and other details to set the tone of the movie and even to cue the mood of a scene. Their work builds the setting into a very real experience. They create the world the characters inhabit. There would be no movie without that.
The characters themselves are built up in the same careful way. The costumes and makeup do much more than simply make the actors and actresses behind the parts look great (or ugly). Clothing and makeup reveal personal details about the characters on many levels. Clothing and makeup send messages to the viewers about who the character is as a person and how that character fits (or doesn't fit) into society. A costume change or subtle makeup change can signal shifts in personal development (such as losing innocence or gaining experience). The costume and makeup of each individual character builds the character. The actors and actresses playing those characters, no matter how brilliant, simply could not play the part if they did not look the part. Although the acting is essential, the character would fall flat without the right look. The magic of the screen hinges on vibrant characters to carry the story.