The author recognizes that although space junk does not pose any danger to humans, it can interfere with the functioning of satellites, which can indirectly harm human life.
We can arrive at this answer because:
Space junk refers to any type of device, substance, and element that has been taken into space by humans and abandoned there, after use.
Most of the space junk is composed of deactivated satellites and defective probes, but any material abandoned in space can be considered space junk.
The author of "Space junk or space history" recognizes that this space junk does not pose a direct risk to human life, or space exploration, however, a conflicting point is that this junk can collide with satellites that function and promote essential elements for the modern life. This can cause indirect damage to human life.
