Many of the Grimm tales in their original form were also somewhat bizarre or surreal. I agree with you, but sometimes think the Disney versions were crafted as they were in part just to make sense as much as anything.
not just them, look at "thousand and one nights", but not at an adaption, look at something close to the original, these used to be very cruel, also the old Russian folk tales used to be quite cruel.
I think they all used to live in a very different reality, with people dying at an earlier age and much more often then they do now. Also infant mortality was much much higher in the olden days; it was a scary time, altogether.
The olden days didn't have the luxury of clean water, antibiotics and food plenty. These are quite recent inventions...