Yes, the Germans had to be stopped.
We should have went to war because we didn't want to get destroyed by the Germans, and plus we wanted to help the countries we were in alliance with. Also if we wouldn't have went to war, then the Germans would rule the U.S. just like how they pretty much ruled all of Europe.
Not America's fight
It's true that the German sank the Lusitania and sent the Zimmerman note to Mexico but entering World War 1 just made it worse because more Americans died. Also many soldiers were drafted into the war between the ages of 18 and 30 which meant they lost a lot of that generation. Also they should have stopped sending more supplies to the allied powers than the central powers.