What cultural ideas are represented by the Harlequin in the story "Repent, harlequin! Said the Ticktockman"?

The Harlequin represents the individualist, the non-conformist, the trouble-maker who defies the rigid conventions of society, and in doing so, exposes their manifest absurdity.
A cursory glance at any great social movement in history, whether it's the civil rights movement or the campaign for women's suffrage, will show us that it is such people who make change happen. The Harlequin's motivations may not be quite so noble as those dedicated to radical social change, but he does have an effect all the same. Anyone who can make the Ticktockman three minutes late has achieved a remarkable victory, even if it's nothing more than a baby step on the road to long-term change in this regimented society.
The Harlequin may not see himself as such, but in exposing society's norms and values to ridicule, he's something of a revolutionary. Whatever his reasons for engaging in such playful subversion, the Harlequin is at the very least ensuring that society's unthinking obsession with punctuality will never be accepted in quite the same way.
Like a latter-day Marxist, he's torn aside the veil of ignorance keeping the working-classes in a state of permanent subjection to show them the true nature of their condition. Once again, the Harlequin may not realize it, but in waging his one-man war against the system, he's raised the consciousness of those at the bottom rung of society, those most adversely affected by the tyranny of the clock.

Ellison's story invites the contemplation of the value of societal regimentation and conformity versus the value of individuality and unpredictability.
The Harlequin is a representation of a catalyst for societal change. He is a revolutionary, an activist, and an anarchist, a man who by his essential nature represents a threat to the status quo; in this case, that is the forces that regiment and regularize society. His whimsical forms of protest do not seem benign to the Ticktock Man; to him, he is a disruptive force that must be contained and controlled but not martyred. In the end, he is forced to become a tool of the establishment, though he has effected change in that the Ticktock Man himself unwittingly becomes late. The Harlequin, known as a fool or a clown, represents the idea that a single person's actions can influence change or even spark a revolution.