Two guesses as to where I am going with this and the first one doesn't count. OK, OK... too obvious :) , but first consider the etymology:
Is a prodigy a genius or a monster — or both? Nowadays, it's the talent that shines through, but back in the 15th century the word's meaning was more strongly influenced by that of its Latin ancestor, “prodigium,” meaning "omen" or "monster." Back then, a prodigy could be any strange or weird thing that might be an omen of things to come. Even in modern English, the word sometimes refers to an extraordinary deed or accomplishment.
Messiah [You guessed it! That's where I was going!] was indeed someone who was extraordinary. Extraordinary does not mean "extra" [excessively or exceedingly] "ordinary" [plain or lacking in distinction]. In this case the "extra" prefix has the Latin meaning of "beyond" or "above" and thus we get "beyond the ordinary": something rare and special and, indeed, Messiah, is truly that.
Although it often does so today the word "monster" should not necessarily imply thoughts of Hitler, Frankenstein's creation, or large water critters from Loch Ness. Merriam-Webster provides 5 definitions for "monster" including these two:
1b one who deviates from normal or acceptable behavior or character 5 one that is highly successful
These can both be used to describe Messiah. He deviated from the sinful behavior and character of those of His day and He was utterly successful in a way that no other person throughout all of history can be: He took upon Himself the penalty of the sins of mankind.
An omen is "an occurrence or phenomenon believed to portend a future event" (also from M-W). Messiah's first appearing was definitely an omen of future events. Since He lived, died, arose again, and ascended into heaven we can trust that He will (as He foretold) return again. In that sense He was an omen but what is the future event that was foretold? A day of coming judgment, atonement, and dwelling among His people (pictured by the fall festivals spoken of in Scripture: Yom Teruah, Yom Kippur, and Sukkot).