Bread is difficult to make even with an oven. However, it can be made without an oven, but it will be even more difficult to make. Before ovens, people would place dough outside in the hot sun in order to bake, but the dough was flat and the bread turned out flat as well. It would not resemble the risen type of bread we see today.
There is a way to make bread without an oven and it is rather easy. It is by using a breadmaker. This is not your standard oven and it is not called an oven, but it technically is. It heats the bread inside the contraption without using a standard oven. The bread without an oven would probably take different ingredients.
In short, yes, you absolutely can make bread without an oven. There are only two ingredients and they are as simple as pancake mix and water. To be specific, the "only add water" pancake mix. If you're cooking over a fire, place the dough on the coals and watch them cook 1-2 minutes on each side.
You can also use this recipe and instead wrap the dough around the stick or place in a tin can. If you have a slow cooker, you can also make a loaf of bread in it! Use your favorite dough recipe, line your cooker with parchment paper, place the uncooked loaf in on high, and let cook for about an hour and a half to two hours, checking on it regularly.