The actions — and in some cases, the absence of actions — reflected the ways the teams and the league struggled to respond to the protests, which began in August 2016 when quarterback Colin Kaepernick, then a member of the San Francisco 49ers, did not stand for the national anthem to highlight his concern over racial discrimination and oppression in society.. Kaepernick’s contract expired after the 2016 season, and he has been out of a job ever since. He has filed a grievance accusing the N.F.L.’s owners of collusion.

While a few dozen players were still protesting at the end of this regular season, the fact that hundreds of players took on complex social issues and didn’t suffer repercussions amounted to progress for player rights in a league known for demanding that its employees subvert themselves and march in lock step, several longtime observers of the league said.

The protests “sent a message of solidarity and cohesion, and made people understand that these guys are entertaining you, but they also have thoughts and ideologies and take a stand on issues,” said Charles K. Ross, the director of African-American Studies at the University of Mississippi and the author of two books on African-American professional football players. “You can’t simply hide in a hole and not have an opinion on these things.”

The moment that changed everything occurred in late September, when the president attacked the N.F.L. at a campaign rally on a Friday night in Alabama. He used a derogatory word to describe players who did not stand for the anthem and called on owners to fire them. His comments sparked a crisis at the N.F.L., which would be playing games less than 48 hours later.