The jpg should be called folder.jpg. It looks like you have a character before the word “folder”. I think it’s an exclamation mark or an i but hard to see clearly. Rename it to folder.jpg. Then you’ll have to reboot your device as the picture will be cached so when you rename it, it will still display the old picture until you reboot.
Because there is no folder.jpg, the device will use the first metathumb (alphabetically) that it finds, which in this case is the Batman Begins one.
the metathumbs tend to take over the jpegs, that is a ! in front of folder, thats how I used to fix before I got away from metathumbs and went to themes.