Gosh your username is mesmerizing. But to answer your question:
Because man (Adam) was put in charge of God’s creation (Genesis 1:28 “subdue [the earth] and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.”)
Adam was to manage the earth and animals; he was (in a way) the link between God and the animals.
When he failed in / abdicated his crucial position, all of creation suffered and was affected with death and decay. It’s like a father abandoning his role as provider: the family under him will suffer.
This is why Romans says “creation waits in eager expectation for the children of God to be revealed”, i.e. when creation will be finally renewed at the end of time.