A platitude is “a flat, dull, or trite remark, esp. one uttered as if it were fresh or profound”. It can also refer to “lack of originality” in general.
It comes directly from the French word platitude, which means “flatness”. Unsurprisingly enough, platitude is related to the word plate.
This word sounds like a synonym of truism, “an obvious truth (often hardly worth mentioning)”. It also reminds me of a pleonasm, which is “a redundant expression”. I wonder how many more words there are for redundant or unoriginal phrases. Can you think of any others?