It also might help the others if Nick didn't keep saying Adalind left me.

She did have a choice she could have been upfront with Nick that Black Claw had Diana she could have talked to Nick about what to do she and Nick could have tried to find a away to protect everyone but she didn't choose to do any of that she chose to take Nick's son into danger.

I don't think Renard wants to kill all humans I think he has made himself believe that he can save them that he can still be a good guy though he is delusional if he believes that.