"B" is a little two-story cabin, maybe:)

So, you and your kids are doing some hiking in Mesopotamian caves, back in the day, and you go into this one cave, bringing your flashlights of course, and you see on the ground some old pots and pans and stuff. Then you notice on the walls of the cave some PICTURES, drawn with sharp knives into the rock, of Animals and Buildings. These are very primitive pictures, but it becomes clears as to what the early people were drawing. Is it possible that these Pictures became, over many years, our Letters?