Then the Germans sank the Lusitania and became the chief bad guy.
In WW2, as others have mentioned, the US was more concerned with the plight of the British (would they hold out?), and then especially focused on Japan. Japan attacked Hawaii and subsequently the Philippines, which was owned by the US at the time and home to a lot of Americans.
Certainly the US played a role in every theater in WW2, but there were almost two different wars going on —- in Europe, primarily Britain and Russia versus Germany; and in the Pacific, primarily the US against Japan.
The Zimmerman Telegram helped, too.
In the beginning of WWII (not sure exactly till which years but at least 39-41), the US only fought in Europe via pilots (the UK greatly lacked pilots), and transport boats. The ground troops only arrived before D-Day at which point the US did get [more] involved in the WWII in Europe.
[1] https://en.wikipedia.org/wiki/Neutrality_Acts_of_the_1930s#E...
With WWI the British were still the preeminent economic power.
No. The USA public was isolationist until the bombing of Pearl Harbor. Germany stupidly declared war after Pearl Harbor in sympathy with Japan.
The key things to understand about WW2 are:
1) Germany and Japan declared war on a country they couldn't invade because of geography.
In other words, the USA did not have enough deterrence at the time to prevent WW2. [paraphrasing Victor David Hanson]
The B-29 was the ultimate weapon in WW2, not the atomic bomb (which was dropped from a B-29.) So much so that Russia spent vast resources after WW2 copying it down to the last rivet.
2) The USA was already the "arsenal of democracy" a year before Pearl Harbor. Historians regard Pearl Harbor as more of a trap than a victory for the Japanese, which would have required both sinking all of America's carriers plus a successful land invasion of Oahu to end well.
3) All sides thought that bombing the enemy's cities would break their will to fight. As any chess player knows, people will fight to the bitter end with very few exceptions.
If by US you mean the public, many in the public did care, insofar they were aware. Generally not enough to want refugees in their country, but they still wanted to see the atrocities of the Nazis condemned by their government more than they were.
But if by US you mean the US government, parts of it were bothered enough to block reports, at the very least:
https://exhibitions.ushmm.org/americans-and-the-holocaust/ma...
> In early 1943, US State Department officials blocked reports about the mass murder of Jews from reaching the United States. Some at the State Department wanted to avoid any increase in public pressure to aid Jews and thought that if the American people did not have information about the atrocities, they would not protest.
[..]
> In November 1943, a group of congressmen, influenced by activist Peter Bergson, introduced bipartisan resolutions in the House of Representatives and Senate calling for President Roosevelt to create a government commission to rescue Europe’s Jews. In secret testimony before Congress, Assistant Secretary of State Breckinridge Long declared that the State Department already had admitted 580,000 refugees, a claim soon publicly proven false.
> At the same time, US Treasury Department staff investigated the State Department’s delays and obstruction in sending relief into Europe to aid Jewish refugees. They discovered that State Department officials had deliberately suppressed reports about the murder of Jews. Secretary of the Treasury Henry Morgenthau Jr. agreed to present their findings to President Roosevelt.
> As a result of Treasury’s efforts, Roosevelt signed an executive order on January 22, 1944, establishing the War Refugee Board. It was charged with the rescue and relief of victims of Nazi oppression as long as it did not interfere with the war effort.