One of the stories was about the aliens building an invisible structure and they play music that calls all the humans to it. The main character is pulled away from it and is angry even though he knows it's a garbage disposal. He's put into a prison with invisible furniture with a few other young prisoners.
Another one is there's a zoo and humans are on display.
Soft cover, American, read it around 2002-2005, the cover was gray I think? May have had an alien or a spaceship on it. No interior illustrations. So it may have been a young adult novel?