Well, no. There was a stand-off, a war of nerves. That could have lasted longer. Confederates could have waited until Lincoln fired the first shot. But they didn't. Once the shooting started it was war and there was no going back.
Comparing Fort Sumter to some later, worse incident doesn't change that fact. Jefferson Davis and the Confederates weren't Hitler and the Nazis, but that doesn't mean that Northerners were going to ignore the beginning of the war. Insults to the flag were serious things back then.
LINCOLN's policy OTOH was strangling the American South labor/resource-rich cousins unfairly with high tariffs and import taxes; Ironically treating the South like ITS slave.
The tariff had only been passed a few weeks before the secessionists started the war. Everybody expected that there would be some upward revision of import duties. Southerners could have stayed in Congress and kept the expected increase to a minimum if that was what they really wanted. But they didn't. The secessionists wanted a country of their own to safequard their "domestic institutions" (slavery) and the leaders were more than willing to risk war to get independence and territory.
Lincoln was landing men at Ft. Sumter. He was going to reinforce the fort. Had they done nothing, they would have been facing even more soldiers and guns at Sumter than they were before.
The act of attempting to land those men to reinforce Sumter, after assuring everyone that he would not, was an act of War.
Even Major Anderson more or less said it was a chickensh*t underhanded move.