I think short stories are useful for learning to read. You can also look for books that have English and your native language. That way you can read several times to reinforce any new vocabulary. If you try to read a whole book, the new vocabulary might be too discouraging. A major part of English literature involves using an expansive vocabulary and often native speakers may not be able to understand many words, so try not to be discouraged if there are too many words you don't know. I recommend The Old Man and the Sea by Ernest Hemmingway. While it's not a short story, it uses a lot of simple language and is an enjoyable book at the same time.

I have heard that graphic novels are a good starting place for new English learners because they add context to the words used. These can be as simple as American comic books or graphic novel versions of classic literature like "Moby Dick," "Great Expectations," "The Call of the Wild," "Romeo and Juliet," or "Don Quixote." I hope that you can find something that might help you in these options.

This might be a bit too low, but I really enjoyed the magic tree house series. It's about these young children that go on adventures through history. I used them to practice Spanish when I was younger and find that they have a fairly basic vocabulary that makes it easier to learn. If not, I also really like the Gordon Kormen books. They aren't very complicated, but are interesting. As for non fiction, there is a company that makes reading books for kids learning to read. If you search level 4 reading kids book, you might find it.