When writing a novel a writer should create living people; people not characters. A character is a caricature.
Authenticity breeds realism and therefore, confidence in the writer. Don’t write about how you think the homeless guy on the corner speaks. Go talk to him. Listen to him, listen to his stories. You have to know your people just as well as you know your setting and plot. Drawing arbitrary, one-dimension “ideas” of characters is not the same as demonstrating the heartache, the joy, the real human connection in that old man. Don’t sell yourself or your readers short. Give them authenticity from the first page. They’ll thank you for it.