Continuity mistake: The Power Chamber drastically changes between the previous series and this one (for example, the old Rangers' costumes and weapons aren't shown), yet no explanation is given.
Continuity mistake: Only a minor mistake - when Japanese footage is used, the Rangers, Elgar, Rygog, and Porto look slightly different - for example, Elgar & co. look more menacing and detailed (compared to their American counterparts), whereas the Rangers costumes are made of a different material.
Answer: The Rangers are human. Blue Centurion is a robot/cyborg.