[Serious] The Story

[John 6IX Breezy]

It makes a difference to judaism, and it clearly makes a difference to you, as your rejection of all of this content is specifically predicate on your belief that it is a prophetic book.  That, likely, influences your belief that it was composed in the sixth century, as well.

This page seems to describe why Daniel isn't a prophet in Judaism, and I agree with pretty much all of it. They just use a more nuanced definition of prophet while we use a broader one.

ps. I'm also not finding evidence that Jewish traditionally believe Daniel was written in the second century. I've actually found a few Rabbis arguing against such a position, and their arguments are pretty identical to traditional Christian ones. Here this Rabbi mentions that the introduction to Daniel was written by the Great Assembly in the third-person (which I have no issues with), and that the second half was written by Daniel in the first-person (which I've alluded to).