No, it's not about picnics or barbecue. It is about people who actually LABOR to make a living - people who work and make products or sell products. It's not about people who invest their Wall Street "winnings" to reap more winnings and then pay a pittance on their capital gains. Those of us who actually work for a paycheck are the only ones who pay our full taxes, don't have offshore accounts or holdings in non-existent companies or blind trusts.
I am going to refer you to two links that are worth reading. They are tributes to the PEOPLE of America who know what it is to WORK for a living. The people who have worked to improve working conditions, wages and benefits for every worker, whether or not those workers are unionized.
Workers' Rights are Human Rights
Skydancing - Labor Day: Celebrate the 99%
Trust me, both links are worth your time.