BlueprintGetters are more like overrides for the standard get method of BlueprintReadOnly variables. This allows you to make the additional checks or replication or whatever is necessary.
The UPROPERTY() is already implicitly BlueprintReadOnly when using BlueprintGetter = FunctionName.
Following from that, to “get” the variable in the blueprint graph with your current setup you would search for Alive, not IsAlive.
Though, if you used the coding standard, the variable would be named bIsAlive and the function name would be GetIsAlive.