After all, isn't it taught that during the time of the Temple there were over a million prophets? And the reason that those prophets whose writings are recorded in the Tanakh are as such because of the importance of the messages they brought?
I am not sure about a million, but I have seen a couple of midrashim and aggadetas that say that there were like a hundred thousand prophets, and we only know of a small number by name, because they were the greatest prophets.
But in any case, those are just a couple midrashim out of an ocean of them. That there were many more than just the handful of prophets whose books we have is undoubted, just from reading Judges and Kings, which mentions groups of anonymous prophets, several times. But how many there were, and what was the nature of their
nevu'ah, and in what way they may have been as "great" or not as "great" as the prophets whose books we have cannot be determined from a few midrashim.
That being said, what would be the point in differentiating between he who hears from and interacts with God for the sake of his personal or communal dealings as opposed to he who does so for the sake of all Israel?
Well, there could be a number of reasons, but the first one that springs to my mind is practical: if a person is a legitimate
navi, one is absolutely obligated to follow whatever their prophecy instructs, as a commandment from God.
But someone who has
ruach ha-kodesh, though their words should be given great weight and consideration, need not be followed as though their dictates were divine. They can be disagreed with, and in fact, sometimes they are supposed to be disagreed with.
when it comes to Ruach, I don't see why that would require any particular level of greatness than the sincere desire and commitment of the individual to follow God's will.
Well, in general, we understand that, while occasionally people will be able to converse consciously with God because God spontaneously opens the communication for His own reasons; for the most part, in order to "hear" God, one must be a person deeply committed to mitzvot or the equivalent good deeds, who has trained themselves with spiritual discipline to raise their consciousness.
And it is not necessarily that those things foster "greatness" in a social, political, or financial sense, but that when they are genuinely present, they foster compassion,
chesed (lovingkindness), justice, truthfulness, and a love of one's fellows.
So it's not that "greatness" is a prerequisite for
ruach ha-kodesh, but that by the time one might be prepared to have it, one is most often "great" in the sense of being an exemplary human being to those around one.
I also don't see why it is that Ruach, while it would definitely be on a lower scale then prophecy, should be defined as anything other than low-scale prophecy.
Perhaps it could be, in a certain sense of the lower-case usage of the English word. But neither
nevu'ah nor
ruach ha-kodesh necessarily have anything to do with foretelling the future, which the word "prophecy" in English is most often associated with; and in our own tradition, a
navi is specifically a message-bearer who must be listened to and obeyed, whereas someone with
ruach ha-kodesh is not necessarily a message-bearer, and might not always need to be obeyed; and also because one can make oneself more open to
ruach ha-kodesh, can in some tiny measure "call it" to oneself, but God picks
nevi'im, and does so purely for His own reasons, not necessarily based on anything specific in the person's conscious aims or goals.