People, I think.

People believe they are individuals, because they sense their bodies as separate from the floor, walls, and furniture - and from that perspective they are correct.

In the same way, people believe their ideas are personal, because they sense personal enjoyment by the sudden emergence of certain "emotionally-tinged" thoughts - usually, just memories - and irritation by the sudden emergence of other people's thoughts.

But, it's all a sham. Look how readily each and every one of them, pepper their speech with the quotation of others, even going so far as correctly attributing those quotations (though usually, they fail to do that). They derive a real sense of enjoyment in that activity - quite mechanical to them - and that enjoyment, from speaking/writing someone else's idea(s), supports their own belief of individuality.

People (the mind) are playing dress-up, and the suit of clothes in which they dress themselves up, are those others whose ideas they so freely speak and so-conveniently forget to correctly attribute. Fred "sees" himself as Mr. X., and so he speaks Mr. X's ideas as though they came from his own understanding. Mary "sees" herself as Mr. Y., and so she speaks Mr. Y's ideas as though they came from her own understanding. And Fred and Mary, remain completely in the dark, as to what is really going on.

But, don't fret for Fred, don't mope for Mary - hell, they don't.