Sin means ‘missing the mark’. That would imply knowledge which implies agency. Babies would be naturally excluded, plus Christ makes special exception for them in the NT.
Death is a result of sin. With no sin, there can be only a sacrificial death. That's only happened once. If babies had no sin, they wouldn't die.
plus Christ makes special exception for them in the NT.
Chapter and verse. Did Herod make the same exception for them?