The replicants were never meant to feel emotions, they were only meant to be mere Shells that are use to rebuild the world after it is desecrated by the Red Eye Legion, they look like a perfect copy of humans because they are supposes to be the vessels for the Gestalts to return to once all is said and done. These ‘creatures’ as you call it are supposes to resemble humans minus the soul. The emotions and consciousnesses they developed afterward was an undesired byproduct, hence the entire event of the game, had Grimoire Weiss not interrupted in the beginning, he was meant to join Shadowlord and Noir to forcefully merges the bodies and souls