If someone was just starting out as a writer and was looking for an example of a well-structured and clearly-formed novel, one that was easily analyzed and short enough to remember all of the important elements at once, I would recommend Anton Chekhov's "The Duel." It's actually a novella instead of a novel, but it's got all the pieces of long-form fiction you need to see as a beginning writer:
There is a complete story arc with rising action, surprising complications and a surprising resolution.
There is a large cast of characters, most of whom add contrast and have some kind of emotional stake in the primary conflict.
There is a clear three-act structure, if you're into that sort of thing. The story falls naturally into beginning/middle/end segments.
There are a variety of points of view.
There is dramatic action, emotional revelation, comedy and beautiful language.
I don't think that reading/writing short stories is a very good way to prepare a writer for the task of the novel, though most of us begin by trying to write short stories. So I've been keeping an eye open for short novels that would be good, clear examples of structure and craft. The problem is that most novels are too large and complex to be really easily understood at the level of mechanics and craft to be useful as a learning aid to beginners. "The Duel" is short enough to read in one day but long enough that the author had to do real work to sustain the reader's interest, to create enough complexity within the story to justify the length. All of the basic elements one could want in long-form fiction using a traditional structure are on view in Chekhov's novella.*
Possibly, when I was writing my first novel long ago, reading "The Duel" wouldn't have enlightened me about how a book is written because maybe without the experience of having struggled against a novel, one can't actually recognize the constituent parts of one. I don't know. But if I were going to teach an introductory course on writing a novel, "The Duel" would be the first required reading I'd give to the class.
I briefly considered Hemingway's The Old Man and the Sea to be a useful sort of "beginner's novel" in terms of structure and evident craft, but that novella has essentially just one character so it might be a bit too simple-minded an exemplar. Though the three-act structure is really obvious in it.
*This is not to say that "The Duel" is a 'simple' or 'basic' story. But the structure is simple enough to grasp, and open enough to adapt to other works. Which is the whole point of using examples, right?