Traditional pumpernickel bread is made with a significant portion of rye flour, which gives it its distinct flavor, color, and dense texture. The rye flour undergoes a unique, lengthy fermentation process that contributes to the characteristic taste of pumpernickel.
While it's technically possible to make bread and call it "pumpernickel" without rye flour, it would not be the authentic pumpernickel bread that most people associate with the name. The rye flour is a key ingredient in the traditional recipe, and omitting it would result in a different type of bread.
If you don't have rye flour or cannot consume it due to dietary restrictions, you can explore other bread recipes that don't call for rye flour. There are various types of bread you can make using alternative flours like wheat, spelt, barley, or a combination of flours to achieve different flavors and textures. Each type of flour will impart its unique characteristics to the bread, so you can still enjoy a delicious homemade bread without rye flour.