We have a difficult time believing a human amputee can regenerate a missing limb. It’s because we don’t observe this in nature. Humans just haven’t been able to do this (yet) even if we see it with Salamanders.
On the other hand, it’s much easier to have faith that someone can cure cancer without the assistance of science because, in some extremely rare cases, it’s happened.
A couple of things: What we can detect and understand changes the story we tell ourselves. Yet, we quite often put our faith in processes without fully understanding how things work. And sometimes, we throw out the science to tell ourselves a completely different story that narrowly defies the laws of nature.