¿Por qué me han rechazado cada una de estas fotos?

I agree with Jill.  Also, I think the two duck photos are underexposded, especially the second one.  That should be correctable.  The trick is to lighten the image without making the glare on the water overpowering.  Raise the midtones and shadows but not the highlights.  
Lastly, the first photo shows a company name in large blue letters on the side of a building.  That will need to be edited out or else it will be rejected for an intellectual property violation.

Soft focus, lack of detail and artifacts, probably from a camera with a small sensor (mobile phone?) are the most noticeable issues. The final image would have needed an IP release for the statues.