Heat 2 tablespoons olive oil in a large soup pot over medium heat until shimmering.
Add 1 yellow onion (diced), 1/2 cup celery (chopped), 4 garlic cloves (minced), 1 small jalapeño (minced, optional), 1/2 cup green bell pepper (chopped), and 1/2 cup red bell pepper (chopped). Cook, stirring often, until the onions and peppers are soft, about 6 minutes.
Stir in 2 tablespoons tomato paste and cook, stirring, for 1 minute.
Add one 30-ounce can diced tomatoes (no sugar added) and 3 cups low-sodium vegetable broth. Add 1 teaspoon dried oregano, 1 teaspoon dried basil, 1 teaspoon dried thyme, 2 teaspoons smoked paprika, 1 tablespoon chili powder, 1/2 teaspoon dried cayenne pepper, 1 teaspoon kosher salt, and 1/4 teaspoon ground black pepper. Stir to combine.
Bring the mixture to a simmer, then reduce the heat slightly and simmer uncovered for 20 minutes, stirring occasionally.
While the sauce simmers, drain and rinse the 15-ounce cans of butter beans, kidney beans, and black beans.
After 20 minutes, stir in 3 cups cooked brown rice and the drained and rinsed beans. Simmer uncovered for another 5 minutes to heat through, stirring occasionally.
Remove the pot from the heat, stir in 1/4 cup chopped fresh cilantro and 1/4 cup chopped fresh parsley, and serve hot.