Lindbergh wrote prolific journals, several of which were published, including "The Wartime Journals of Charles Lindbergh". I read them many years ago. He was more isolationist than anything else, in part because he had been given a great deal of access to German officers and airplanes. He actually was allowed to fly an Me-109, which was a far superior plane to any fighter in our inventory at the time. Lindbergh didn't think we could win against Germany so he wanted us to stay out of the fight. His view wasn't without some merit. In the mid to late 1930s, the US military ranked about 18th in the world behind such international powers as Denmark. Among other errors, I think Lindbergh didn't realize how quickly the US would ramp up production of good weapons like the P-51.

As for old Joe Kennedy, he was considered a defeatist, especially by the British. They hated him as an ambassador. He was convinced that Germany was going to win the Battle of Britain, which they almost did.