There’s just something so timelessly English about Away in a Manger, O Little Town of Bethlehem and We Three Kings, even though they’re all from the US. There’s something so Christmassy about Wenceslas and Ding Dong Merrily on High and Jingle Bells even though none of them mentions Christmas, and Jingle Bells (which is also American) was written about Thanksgiving.
But somehow these carols work, and so do all the others.
http://www.bbc.com/culture/story/20161220-the-surprising-origins-of-famous-christmas-carols