Kikyou is a mere mortal even after 50 years since her death?

This statement is true within the Inuyasha narrative. Even though 50 years have passed since Kikyou's death, she remains a mere mortal (undead but mortal) when she is resurrected. Her soul was reincarnated as Kagome, so Kikyou is sustained by dried demon bones and soil, not true immortality. She retains human vulnerabilities and can 'die' again, making her fundamentally mortal despite her undead state.