What were Jesus's 'Miracles' supposed to prove?
Good question. Of equal importance is how he considered persons who were skeptical of his miracles.
13 “Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles that were performed in you had been performed in Tyre and Sidon, they would have repented long ago, sitting in sackcloth and ashes. 14 But it will be more bearable for Tyre and Sidon at the judgment than for you. 15 And you, Capernaum, will you be lifted to the heavens? No, you will go down to Hades. Luke 10:13-15 New International Version
So, he supposedly forgave his murderers but damned to Hades those who disbelieved. And why were these people supposed to believe when magicians were a dime a dozen in the ancient world. A sincere and rational person would have been, in the mental framework of that time, willing to believe if there were proof that his miracles were legitimate but their religion would consider the possibility that a 'miracle' would come from Satan. So how does one tell the difference?
From that attitude, as well as from non-theological skepticism, one would first question the recipients of those 'miracles'. Did they know them personally? How do they know that Jesus had not slipped a silver coin into the hands of a healthy person instructed to act blind or hunchback?