I’m a former member of SCBWI which is the professional organization for children’s writers and illustrators. A few things. You shouldn’t submit images with picture books unless you are both author and illustrator. They shy away from rhyme because it’s simply difficult to do rhyme well and many can’t. They don’t like message driven books that are preachy. Instead they look for a well woven story that leaves a message and they like universal themes that resonate with children. They look for books with a strong voice and a sense of rhythm to the writing.