Here are a few more that i loved as a young child: Mary Poppins Mrs Piggy Wiggle Ramona the pest The OZ books, although some of them are a little scary. the little prince The mumin troll books by Tove Jansson The last unicorn And as mentioned above, the little house books- my all time favourite. I can't wait till DS is old enough to appreciate them.
Astrid Lindgren's childrens books are wonderful. I am sure your DS would love the books about Lotta, Madicken, Emil and the bullerby children. I'm not sure what the are called in English but that should be easy to find out.
loads of Dick King Smith ones (might edit out a few - I have for my girls but on the whole they are great) Traditional Paddington chapter books - absolutely lovely to read, no fears about content either. Wishing Chair - Enid Blyton Naughtiest Girl in the School Something like Snow Bear by Holly Webb? I haven't actually read it - we have it on the bookcase but I imagine it is a lovely story as her other books are perfectly harmless. Charlotte's Web? Mrs Pepperpot? Mr Benn - you can get a hardback book with a few Mr Benn stories in Milly Molly Mandy
I think all of those would be suitable for a little boy, especially if he is quite sensitive.
Little House in the Big Woods (but probably not the later books), especially interesting to hear the differences / similarities between life then & now. Teddy Robinson - absolutely perfect for a 4 y/o esp one who is a bit sensitive The Sophie books by Dick King Smith, ideal in that they are about day-to-day life, but Sophie is a great heroine, very funny The No. 1 Car Spotter