While a debate over professional football players kneeling during the national anthem consumed much of the country over the weekend, a scene was playing out around St. Louis that drew far less notice. There, demonstrators protested the acquittal of a white former police officer in the fatal 2011 shooting of a black man, marching inside a mall and through the streets in daily protests over the case for more than a week.

Around the country, racial justice activists are concerned that the essential issues they have spent years trying to highlight — police brutality and systemic racism — could get lost in the growing national dialogue emerging from football stadiums.

When Colin Kaepernick, the former San Francisco 49ers quarterback, first made headlines last year by sitting during the national anthem, he made his motive clear: He was protesting racial injustice in America, especially the police killings of black people, an issue that began drawing increased national attention after the death of Michael Brown in Ferguson, Mo. in 2014.

But now, with President Trump criticizing the N.F.L. and its kneeling players, leading many players, owners and league officials to band together, motivations have become murky, racial justice advocates and protesters say. Are they fighting for free speech or against police brutality? Is the anti-racism message of kneeling being co-opted by a league and owners more concerned about their bottom line than black lives? Why is there so much talk of what it means to stand for the national anthem and so little about Anthony Lamar Smith, the black man who was shot in 2011 by the former St. Louis police officer?