This fact alone increases the likelihood that Shakespeare translated this work.
No, it doesn't. First, because we already know that Shakespeare of Stratford wrote the works -- at least according to the statement of Heminge and Condell, who knew him well, and owned the rights to most of Shakespeare's works produced for the acting company they all were sharers in. Second, the Metamorphoses was influential not only on Shakespeare, but also other writers. The use of an "un-" prefix in Golding's Ovid was a trick Shakespeare took to heart. This is far more likely than the Earl of Oxford making a lifetime practice of using a series of stand-ins for his works, none of whom ever reveal that they served that purpose.