iPhone Not Showing Notification Content in Banner
In your screenshot of your current settings you are actually on the correct page, you just hadn't scrolled down far enough. If you go back to 'Settings > Notifications > Messages' and scroll down to below the "Messages Options" section the feature you want to enable to fix your problem is called "Show Previews".
Hope this helps! And if it does not fix the issue you're having could you post a new screenshot of what it shows below the "Messages Options" cutoff point in your original 'Settings' screenshot?