“Intentionality” is a philosophical term for “aboutness”. A movie review is about a movie, and the sentence “Trump is a narcissist” is about Trump. Your thoughts concerning today’s breakfast are about today’s breakfast. Each of these is about something else, so each exhibits intentionality.
How do these things acquire their aboutness? “Trump is a narcissist” isn’t inherently about the man who bears the name “Donald Trump”. Had Trump’s family retained their Germanic surname, Drumpf, then “Trump is a narcissist” would no longer be about the man we call “the Donald”. The intentionality of the sentence is derivative; that is, it derives from the pre-existing convention of referring to a particular man as “Donald Trump”.
Where does the buck stop? If A derives its intentionality from B, and B derives its intentionality from C, it would seem that we must reach a point at D or E or later in the sequence where the regress ends and the intentionality is intrinsic, or original. What is that point?
For many philosophers, that point comes when we cross the line between the non-mental and the mental. For them, thoughts have original/intrinsic intentionality, while spoken or written sentences do not.
My own belief is that original intentionality doesn’t exist, but I’ll leave my argument for the comment thread. I know that others here do accept the existence of original intentionality, so the discussion should be lively.