The short story is a great way to learn about the elements of craft. You can explore and refine characterization, conflict, point of view, and setting, all of which are important in both the short story and the novel. And you can even experiment more widely, tackling a first person point of view in one story, for example, and third person in another. Writing a short story isn’t easier than writing a novel. In fact, some writers find the short story more difficult. But exploring and experimenting in the bounds of a seven page story rather than a two hundred page novel can feel more manageable to newer writers. It can also help you develop an understanding of your individual skills and preferences as a writer.
However, there are significant differences between short stories and novels. Conflict, for example, must be introduced, developed, and resolved quickly in a short story, whereas a novel demands a broader scope and more development to sustain tension. Figuring out how much ground you can cover, and how to negotiate the increases and plateaus in each form is something you can learn only from practicing and reading that particular length.
So don’t feel hemmed in by short stories. If you’re ready for that novel, by all means get started. You will learn a lot about fiction, much of which can only come from writing a novel. But you might find the shorter form a comfortable way to develop your skills if you’re feeling unsure with the basics.
(For inspiration, you may want to read Fiction Gallery, an anthology of exceptional short stories compiled by Gotham Writers Workshop.)