Given that things are otherwise the same on earth (including humans), I can think of only one alternate reality scenario where this is possible.

Gods actually exist and impact the world...and want human sacrifices. This is pretty strait forward. Appease the angry gods or they will kill the crops and your first born etc etc etc.

I am assuming you are referring only to medieval Europe here as during the medieval era the Mayans were around and human sacrifice was part of their culture.

Another thought just occurred to me. If you expand your concept of human sacrifice beyond the traditional knife, fire, stone slab thing. You could consider the Salem witch hunts, the Inquisition, heck even holy wars as a form of human sacrifice. To "Honor the gods." The sky is the limit (so to speak) if you consider violence and killing in the name of god to be human sacrifice.

Given that things are otherwise the same on earth (including humans), I can think of only one alternative scenario where this is possible.

Gods actually exist and impact the world...and want human sacrifices. This is pretty straight forward. Appease the angry gods or they will kill the crops and your first born etc etc etc.

I am assuming you are referring only to medieval Europe here as during the medieval era the Mayans were around and human sacrifice was part of their culture.

Another thought just occurred to me. If you expand your concept of human sacrifice beyond the traditional knife, fire, stone slab thing. You could consider the Salem witch hunts, the Inquisition, heck even holy wars as a form of human sacrifice. To "Honor the gods", the sky is the limit (so to speak), if you consider violence and killing in the name of god to be human sacrifice.