What general features of earlier American history worked against American involvement in European affairs and participation in the League of...

The major feature of earlier US history that worked to
keep the US out of the League of Nations was the idea that it had tended to get burned
by involvement with Europe.  In other words, when it got involved in European struggles,
things tended to go badly for the US.

One example of this
would have been the US involvement in the Napoleonic Wars between France and England. 
When the US got sucked into this dispute, it ended up almost going to war with France
and finally actually going to war with England in the War of 1812.  A similar thing
happened in WWI.

So the US did not want to be involved with
European affairs because it did not want to be dragged into another
war.