“Daniel” is an example of Apocalyptic literature, which was written to give people hope in times of persecution.  Daniel is like “Revelation” in this regard, which even borrows images directly from “Daniel.” (See Daniel Ch. 7 and Revelation Ch.13

Both Daniel and Revelation look at Jewish  tribulations at the time of their respective writings, look backward in time to past Jewish tribulations, and remind the reader that God delivered His people then, and will in the future, as long as the people keep their faith/return to the faith.

Daniel, thought to be written 167-164BC by most scholars during oppression by Antiochus Epiphanies, looks back at the Babylonian Captivity  (c.605-536BC, see 2Kings 24+25, Jeremiah 52),  places the characters in that former time, shows how perseverance in the faith saves the day, a message that is still true today!

Are these accounts “true?”  See CCC paragraphs 105-119, especially 107,110.

Many today see a further fulfillment of Daniel Chapter 9 (“The 70 Weeks”) in the “End Times” appearance of the Antichrist. To try to understand Daniel 9, read also Jeremiah Ch.25 and 28. In Jeremiah, 70 years (“7” =“complete”) of captivity in Babylon, then happiness. In Daniel, he sees the return of troubles, so the number 70 is reinterpreted to include FUTURE persecution.

(Bible events/ prophecies can have not just one, but several future fulfillments.)