The character, Scarecrow, is a fictional character created by L. Frank Baum. He was the first character to join Dorothy on her journey. When he is first introduced, he is only 2 days old. His behavior is that of a newborn – he simply has not learned how to act/behave/communicate. As we see Scarecrow progress, he already has a brain, he just needed to learn how to use it.
Some consider this novel, particularly the character of Scarecrow, as a political allegory. To some, Scarecrow represents the stereotypes of an American farmer in that era. Farmers were considered ignorant and stupid. In reality, American farmers possessed remarkable insight to culture and society and a strong common sense.