If you mean, "Do ALL Protestants think Calvin was modern prophet?", I suspect you will have to ask all Protestants. I personally don't think he was anything more than an astute Bible student that noticed the Scriptures told an entirely different story than Rome told.
It was not that no one had understood the true Gospel of grace during the prior 1200 or so years (since was beginning to be suppressed in Augustine's time), it is just that the sacerdotal/papist/ceremonial/tradition views of Rome dominated the landscape. Calvin, really after much work by other reformed minded men, simply documented many of the errors Rome had subsituted for the clear teaching of the Bible. It is for these works that many are grateful. But, "prophet"?, no.
It was not that no one had understood the true Gospel of grace during the prior 1200 or so years (since was beginning to be suppressed in Augustine's time)
Who had this knowledge specifically? I am glad for Calvin's work and scholarship, too, but who had this knowledge after the Apostles died or were martyred.