It seems to be obvious that all the Tanah' is prophecy, or at least "Ruach' Hakodesh".
However, we see that the Gmara try to prove that Esther was written by Ruach' Hakodesh; but why there is no such thing for Neviim Rishonim ?
We do not see much such things as prophecy of the past, so wouldn't be more logical to say that those are "just" chronicles ?
If they were just chronicles, they would not have been included in Nevi'im. If you read the book of Kings, you see many times it references the historical records of various kings. This implies that it was not written as just a book of history. Instead, it is a book with a message, and written by a prophet.
The book of Samuel contains the prophecy that King David is G-d's choice to be the king, and that all future kings must be his descendants. This is an extremely important prophecy.
The reason why there is a discussion of Esther and the works of Shlomo HaMelech is that there were disputes as to whether they were part of Tanakh at all. Everyone agreed that if they were part of Tanakh they were written with Ruach HaKodesh and vica versa. The question is if they were.
The question by Esther is that it was written specifically to be read on Purim. Perhaps it was never meant to be part of Tanakh. Perhaps it was not even written with Ruach HaKodesh; it was just a chronicle of a miracle to be recited annually. Therefore the Gemara discusses proofs that it was written with Ruach HaKodesh, and the disputes whether it was meant to also be part of Tanakh.
The question about the books of Shlomo HaMelech is similar. Perhaps these are records of the saying of the wisest of men, and therefore very worthy of study and transmission, but not written with Ruach HaKodesh. Some Tannnaim followed this view. So the Gemara brings proofs to show that these works are more than just Shlomo's wisdom.
