These images are all different and have different issues associated with them. In some cases, there are multiple issues.
File 5188, the composition is poor. It appears to be a casual, shoot from the hip style snap shot. There is little commercial value as is. I would have tried to get more creatived with alternate angles and viewpoints featuring just the chairs or just the tablet, or shifted to the left so it doesn't feel so unbalanced. In addition, you likely need a property release for the building, you need to remove the identifying writing from the top of the table and based on the low resolution screen shot, it appears there is excessive noise in the file.
Image 6848 is a bit crooked, you want to straighten that out based on the lines on the table. It's a distraction as is. The rice looks strangely pixellated and out of focus. The most glaring issue (pun intended) is that huge bright spot paired with the harsh shadow at the top of the image. The lighting was not ideal for this scene. You were almost there but not quite.
Image 1329 is crooked and unappealing in general. The tilted angle makes me literally turn my head to look at the image. That aside, the scene is not aesthetically pleasing. The staircase is dirty and rusty but not in a cool, steampipe fashion, the tree branches are bare and the snow is melted in some patches and doesn't look clean. It's a bit heavy on the contrast in my opinion for a specific technical issue but even without that, I'm not sure what a customer would be able to use this image for.
Image 7654 is the coolest shot in the batch. I like the light, I like the mood of the image. The problem is it appears to be an intellectual property violation. That sign is an identifier of what appears to be a restaurant patio. You can't submit images with visible brands, logos or property identifiers in them. Cool photo though. If I was being nitpicky about the composition I would advise you to remove that blue chair in the lower left.
Image 6856 has noise issues as well as a distracting tilted horizon. The real deal breaker here though is the airline logo on the end of the wing. That's an intellectual property violation.
Best of luck on your future submissions!
Thanks for your answer, I'll try to fix it)
Use the rule of thirds when framing your shots. Good stock photos have a pleasing composition, a subject people are interested in buying and perfect technical quality.