Is Riddick The Last of his Kind?

Could you elaborate on the concept of "Riddick being the last of his kind"? Is this a statement suggesting that Riddick is the sole survivor of a particular species or group? Or is it a metaphorical reference to his unique abilities or experiences? If the former, what evidence or reasoning supports this conclusion? If the latter, how does Riddick's story or character traits make him seem like the last of his kind in a metaphorical sense? Additionally, are there any implications or consequences to considering Riddick as the last of his kind, both within the context of the story and in broader philosophical or societal terms?