What evidence do the authors include to support the central
idea that indian workers and formerly enslaved people
became rivals?

i don't see it in your profile.                                                  

6  then the  lord  said to cain, “why are you angry?   why is your face downcast?   7  if you do what is right, will you not be accepted? but if you do not do what is right, sin is crouching at your door;   it desires to have you, but you must rule over it.”

8  now cain said to his brother abel, “let’s go out to the field.”  while they were in the field, cain attacked his brother abel and killed him.

the excerpt from the passage that best states the author's claim is: "why did people keep speaking of equality while profiting from slaves? "

when pierre lemerre the younger said in 1716 that all men were equal, slavery was reaching its crudest peak and either eastern europeans and africans were treated as objects from which powerful landlords could profit.