I agree with the first answer above. And maybe it is as simple as that in terms of how the question was worded. But I would like to bring a little reality here, since this is what those artistic images actually represent. So... Is this just an edible prop to show austere, unsanitary conditions, or was it really the way it was?
In one case, you have the cowboy on the range and he eats what he is carrying with him, and what he can hunt locally. That probably means a lot of beans. But it also means everything else that his rifle shot recently.
The a broader case, we are closer to people who can cook on a stove and have access to the local economy (like in the picture above). Now human creativity takes over and you have all sorts of foods, much of which was probably quite good. But still, beans were undoubtedly a common ingredient. I have read stories of people riding miles and miles because they heard of a good cook who baked doughnuts (or bearclaw as they called it then).
The cuisine was distinct, but it was not mostly beans.