I saw this cartoon back in the 60's and it scared me. I had nightmares. I just finished watching it after 40 years. Despite the demented nature of the cartoon, I actually found myself laughing in parts. The cannibal eating the people on the bus to get a seat was strangely humorous. The cartoon can be found on YouTube so its time to face your fear. It's really not that bad.
While I wasn't born in the 50's, I did watch a lot of cartoons that were made during that era as a kid in the 60's. Some of them were sort of weird and violent and it surprises me that people found them funny. I guess they worked better when shown in theaters with large audiences.