There were plenty of world wars before WWI. WWI was simply the first in which America played a major role. The empires fought each other across the planet long before America was a thing. Nearly every country was repeatedly involved in these conflicts. War was not an unussual thing then nor now.
"The Napoleonic Wars (1803–1815) were a series of major global conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European powers formed into various coalitions."
"The Seven Years' War (1756–1763) is widely considered to be the first global conflict in history, and was a struggle for world supremacy between Great Britain and France."
