I'm surprised to hear that his books weren't intended as an allegory for Christianity and the Bible. The parallels are hard to brush off as coincidence. The inspiration is increasingly clear towards the end of the series especially. Not that kids are going to read it and convert to Christianity by any means, just that anyone who's read the Bible is going to see a lot of similar themes. It's a great series, but definitely Christian inspired.

Even if they don't look quite like the characters they're playing, from the actors I've seen I think they'll all play their parts well. That matters a lot more than race and appearance imo, even if it's not entirely accurate