Sandwiches suffer from a bit of a misnomer. They've been around since far before John Montagu, 4th Earl of Sandwich claimed his way into history.

In the Bavli Pesachim, it is recounted how Hillel the Elder constructed a sandwich during Passover. He slid slabs of meat between two pieces of matzo. It became popular for Babylonian Jews, and may have been carried back to Roman Jerusalem.

But to really answer your question, we'd have to examine culture-by-culture and era-by-era, a topic restrictively large for a Reddit post. But, for an illustrative example, Middle Ages Europe was quite fond of "trenchers," which were plates cut from loaves of bread. When the meal was finished, these meat-and-veggie soaked plates would be handed out to beggars or kept for breakfast. (Meads' Banquets Set Forth: Banqueting in English Renaissance Drama). It would also be quite usual to see people stack things upon a single piece of bread--often called "bread and cheese" in older literature--or simply eat the bread as a side dish. If that seems strange, keep in mind that ancient breads were a much heartier, much stronger dish.

The nearest equivalent you can find in stores (aside from a specialty baker) would be Ezekiel Bread. I encourage you to try it, and see how different it is than what you would immediately think of as bread (it's also quite delicious, and makes a fabulous stuffing).

It seems like your assuming that people don't eat plain bread anymore, which is certainly not the case. There are plenty of breads eaten plain or with a spread: bagels, pitas, muffins, cakes, cornbread, pitas, toasted breads, pretzels, fry breads from India to Africa to South America, rolls, breadsticks, pastries, croissants, doughnuts, or just really good plain bread.

Or are you interested in historical breads, whether varieties, recipes, serving suggestions or preparation? If so, is there a certain place or time's bread that you'd like to know more about? That way we can attract the appropriate expert.

If you think sandwiches are the only way to eat bread, you really need to get out more.

There is more bread out there besides white "sandwich" bread. Think pita, roti, naan, injera, biscuits, matzo, etc.