This particular section is filled with objects lessons for Jonah because he has a immature spirit - he has got the backbone - but he fails in his heart responses towards God and others the lessons come in the shape of a vine, the worm and the scorching wind
CH Spurgeon wrote “ Jonah here is like a little child going back to kindergarten school where the child like spirit of Jonah had to go. He needed to be taught by object lessons. ” Treasury of the Old Testament 624