Europeans have a longstanding tradition of being really, really weird and really, really suspicious of other people.
Chuck and I just recorded a podcast on totem poles that should be out soon and in the article there's section on totem pole myths, specifically that they were used to ward off and/or worship evil spirits. That would be incorrect: totem poles are instead akin to a very tall wooden family history. Think a bit further, though. Where would that myth have come from? Yes, that's right, European settlers. (I wrote another post on how European suspicions created the idea of witches.)
How about cannibalism? There's a guy named William Arens who posited in 1980 that there's never been a culture that practiced cannibalism. Instead, it was suspicious rumor generated by early contact between Europeans and native tribes. It's not entirely odd, if you think about it. All it takes is an explorer in the grips of awe and cynicism while meeting a previously-undiscovered group of humans noticing there happen to be a lot of piles of bones here or there. Instead of considering the possibility that the people practice funeral rites that don't include burying their dead (true), the explorer concludes that they eat one another (false), high tails it out of there and goes to tell everybody else that the group practices cannibalism. Sadly, the image of bone-nosed natives cooking Bugs Bunny in a huge pot is not a caricature of a real thought, but a pretty accurate portrayal of how whites viewed unconverted tribes.