Hylians are a race (Though this has been said in many games ALTTP and OoT for instance) not just humans in fancy dress and when they refer to human without a capital its humanoid as its a term not a name, Human with a capital is a race. The Alttp retcon is probably due to the hylian blood running thin (which was stated) as they interbred with humans and died out though this situation is special only to Alttp so its safe to assume Linebeck is a Hylian as he displaus Hylian racial features.