Can you recommend some authors who have a simple writing style?

I would recommend Erich Maria Remarque. Most of the people recognise him only from ,,In the west nothings new” and believe that his books are so hard. Of course, the topic: war, redemption, being aware of cruelty of the people, not the world, yours mistakes and crime isn't very easy, however the author writes so touching and softly that these devastating scenes becomes valuable lesson of humanity. However if you think because of previous words that there is nothing hard, and straightforward, only the pretty language to describe mass death of young soldiers, you are wrong. I would recommend at first the ,,Night in Lisbon”, (is about an imigrant who to get a ticket enabling him run away from war, has to listen to a story of complete strangers), ,,Time to Love and Time to Die” (a WWII german soldier comes for few days to hometown where he founds out his parents propably perished in bomb attack. Becoming more and more aware of Third Reich actions and undoubtedly end of war, he knows he will come back to front and propably die fighting for lost causes and barbarism he doesn't approve. Those are very touching, but In the west nothings new is also good idea. I just want to highlight, that his books aren't only about war, they are about finding right person in the cruelest time, finding wright path, humanity, conscience, love, friendship (maybe precisely comrades), mentors and just living, finding faith and power to keep fight in war and far from line of fire.

I hope you will take my recommendation into consideration :)