1, 2. As a synonym for person,individual is standard, occurring in all varieties of speech and writing: Three individuals entered the room, each carrying a sheaf of papers. Some object to this use, insisting that individual can mean only “a single human being, as distinguished from a group”: An individual may have concerns that are ignored by his or her party.
"a single object or thing," c.1600, from M.L. individualis, from L. individuus "indivisible," from in- "not" + dividuus "divisible," from dividere "divide." Colloquial sense of "person" is attested from 1742. As an adj., used from early 15c. meaning "one and indivisible" (with ref. to the Trinity). Sense of "single, separate" is 1610s; meaning "intended for one person" is from 1889.
"A majority can never replace the individual. ... Just as a hundred fools do not make one wise man, a heroic decision is not likely to come from a hundred cowards." [Adolf Hitler, "Mein Kampf," 1933]