One of the main humans was a girl called Steelfinder. The main aliens all look the same and use translators to communicate with humans, and they have another alien that's covered in hair called Forkbeard who is the slavemaster. In the end the main guy gets captured and he shuts off the air conditioning and the main aliens die because the air gets too dry for them to breathe.
I think you might be thinking of "Marauders of Gor", by John Norman.
Former earthman Tarl Cabot has been struggling to free himself from the cruel control of the Priest-Kings of Gor to no avail. As he pits his strength against such a formidable enemy, a terrible beast appears from the mysterious northern lands, bearing a token of the demise of Tarl's once-beloved woman Talena. The missive is a sign of defiance and disrespect from his enemies, meant to humiliate him and force him to challenge them in response. To gird his weapons and set out on a mission of vengeance against those who sent the beasts means Tarl must jeopardize his fortune and position as a wealthy slave merchant. But he is no longer practical and calm as he was on earth. He must conform to the social codes of Gor, where the only way one can avenge wounded manhood is to respond with all one's might!
The "Priest Kings" are not human, but rather an alien, insect-like race that dominates the world of Gor. More information on Gor can be found here.
I don't know who Steelfinder is, but Forkbeard is identified as the leader of a group of slavers in Marauders of Gor. In-book text can be found here.