The sun is almost directly overhead and to your right. Thus only the roof is getting light. This is a midday problem in the summer. Most midday summer pictures cannot pass railpictures.net high photographic standards.

The historical content is immaterial. It's a photographic site of railroad content not a railfan site. Photographically your photo is not that interesting of a picture. It is extremely difficult to be objective about your own photos.

For reference, I have just over a 1000 photographs on the site. Many more thousands have been rejected. I no doubt thought they were all good.

Looking at pictures that are accepted is a good way to see what they are about. This rejection has taught about lighting and interesting subjects.