Don't be discouraged by whatever similarities there are. Your Santaman and Joyce's Santa are different enough to stand by themselves.
Your Santaman concept and cartoon are really good, by the way. It reminds me of the Batman and Superman cartoons I used to watch as a kid and still love today. It deserves to be a TV show, in my opinion.
I still think that yours has great potential. I will echo Shadowcat's comment and say that your characters are quite original and deserve to be seen out there in the world. I look forward to seeing Santaman and how all of those villains of yours will test his mettle.
There are similarities... but your Santaman is way more original and by far more brilliant. Your style and concepts are too good to be copied and if I were you I would get a copyright to it all right away.