I think it would have been more fair/square if the writing credits for "Happy Christmas" song had been written as "Words John Lennon; Music Traditional".
I've never heard that Jewish song before - I suppose if it came before "Give Peace a Chance", the writing credits should reflect that.
John lost a lawsuit on that Chuck Berry song, that's how John's "Rock and Roll" album came to be. For my bit, though I hear similarities, they sound different enough to me that I would not have voted to convict John of musical plagiarism on that one. I suppose Paul took a hit on that one too, being a "Lennon-McCartney" song!
A little OT, but I feel the same about the song George lost a lawsuit on, "My Sweet Lord" (he lost because some judge/jury thought it sounded too much like "He's So Fine", by the (?)Chiffons). They sound different enough to me that I wouldn't have convicted.