It is unfortunate the grade did not include any marks to identify the deductions. Both mechanisms would result in some deductions. I am not sure why the deductions were as large as they were, but the curved arrow should be toward the aluminum, it doesn't have electrons to donate. The resonance arrows are not double headed, and the rearomatization step was missing.
Second problem, you'd have to find my electronegativity arguments that I have posted in the past if you want to know why thiophenol is more acidic. Oxygen is the second most electronegative element, so you cannot use an electronegativity argument. Then you need to apply whatever argument you were given to explain why electronegativity arguments fail. Size or charge distribution are popular arguments.