"introduction to oedipus the king": what is most likely the author's intent in writing about the difference(s) between sophocles's play and the original myth on which it's based?

The author of the introduction is probably trying to show why Oedipus the Kings is a work of literature worth reading, and what is Sophocles’ merit in writing that play.  

There is a gap of almost twenty centuries between us and Sophocles, so the introduction to the book is trying to show you why its themes are still valuable and worth reading today. It also highlights the difference between the fable of Oedipus and the way Sophocles turns it into a work of art.  

1.creeping like a snail is a simile used in this poem and it means the child is going to school unwillingly./a child is unwilling to go to school.

2. man becomes very frail and loses his physical strength when he becomes old, so much that his leggings that used to fit him snugly when he was in his youth are now too loose for him to wear, and that his shank has shrunk so much that this worldly stage is too big for a feeble actor like him. although, 'his youthful hose' just refers to his leggings/pants/ to shrink from danger; to shrink from contact.

3.the words "sans" means "without." it is a french word that is often used in english even today. so he is saying that in the last age of a man, the man is without eyes, taste, or anything else. he also says that this is the "last stage of all" and that it is the stage that ends a man's "history."

hope this !

a term is used to describe a sudden revelation in a short story is "showing forth".