Hi Lukas. For a documentary photo, the first one works, but for an effective composition it is difficult to focus on the subject as the image is very busy. This is one of the reasons why the second image works so well. In most situations, less complex is usually better so that there are fewer objects in the image that aren't in competition with the subject but rather complement it.
In the case of the first image, RED shouts for attention. In addition, consider the image in relation to what you want the viewer to focus on and explore. In choosing the main subject, consider what is the viewer’s eye drawn to:
• Sharp elements before out-of-focus elements
• Human elements before non-human elements
• Faces before other elements, and on the face, the eyes first
• Warm colors over cool colors
• Bright colors over dark colors
• Areas of high contrast over areas of low contrast
• Recognizable elements before unrecognizable elements
• Oblique or diagonal lines before strait lines
• Large, dominant elements before smaller elements
• Isolated elements before cluttered elements
So in this case, for a more powerful image, we might want to replace the Red objects with items of a softer colour and remove some of the non-essential objects on the table and window shelf.
Hope this helps!