Every story has characters. They may not be human, but they should have human traits. Also, there has to be at least two characters in the story. Stories with one character are not stories, but monologues. You can have one person talking in a story, but they should talk about other characters.
Characters do not have to be people. They can be things, animals, vegetables – as long as they act with human traits and can express thoughts and feelings in a way that people can have empathy with. They also need to be put somewhere, in some type of environment, that affects how they feel and helps define them as characters.
After settling on who the characters are and where they exist, there has to be some type of challenge to them. This could be a conflict with other characters, the need to achieve one or more goals, or a combination of these.
From here, a story improves when the writer adds depth by layering and expansion of the characters, where they exist, and their challenge. The best way to do this is through relationships either between the characters, their environment, their quest, or a combination of these.
Another way to provide depth and layering is for the characters to have something in common that drives them apart, have them as opposites that makes them the same, or they transform the other from good to bad or vice versus.
While two characters are the minimum in a story, there can be too many characters. The number depends on the length of the story (less in a short story, more in a novel). I learned from readers over the years that, when a story has too many characters, the reader struggles to figure out who is who (certainly me).
No story is a story without characters.