When Rambam says that a principle of our faith is that the Torah we have today is what was given to Moshe, was he referring to Chumash or all of Tenach?

ב"ה Shalom The Rambam was referring to the Chumash. The Chumash has a unique status since it was given to the entire Jewish people at Mt. Sinai . The words of the prophets were not revealed all at once neither were they revealed in front of the entire nation as the words of the Torah in the Chumash were. Nonetheless, the Rambam enumerated as sixth principle of faith (out of the 13) to believe that all the words of the prophets are true. Furthermore, during the time of the second Bet hamikdash, the men of the Great Assembly set the prophets in their final form under the leadership of Ezra shortly before prophecy discontinued. The 24 books of the Tanach were canonized to which nothing can be added or subtracted. (See Talmud Baba Batra 15 a, Bamidbar Rabba 14:4 , Sefer Chasidim 1016, Bet Yosef Orach Cham 690) Chag Same'ach