@Reshfan No, people's lives are not replaceable. Physical human beings are replaceable, but the lives they lead, the experiences they've had and everything they could have potentially become... those unique existence are gone forever when someone dies.
My personal favorite response to the trolley problem was when Mark Rosewater answered it from the perspective of the five colors in Magic: the Gathering.
White: Pull the lever because the needs of the group are more important than the needs of the individual.
Blue: Pull the lever because it's...
No, you fool! Don't bemoan your current circumstances! You need to start making preparations to avoid dragging the shitty vampire into your harem! USE THAT GENRE SAVVY TO EXERCISE SOME BASIC PATTERN RECOGNITION!
... Welp, he's doomed.