But still, we Humans use leather to create seats and couches, right? Also, Lego people do not have flesh. It is like humans and wood, one is sentient and the other is not. The same thing with the Gingerbread and Lego scenario, the building material is non-sentient and the Lego/Gingerbread people ARE sentient, therefore not made up of the same genes and don't have the same chemical makeup. In a Lego world, it would not seem like you are using corpses to build your house, but different resources like metal and wood, but in our POV, it looks like blocks. If you shift down to a lego/Gingerbread person's POV, it is just a normal world and normal objects to them.