A childhood belief about people

I lived near a graveyard when I was young, and on some of the gravestones it just said R.I.P. I just read it as the word 'RIP', and so I thought that this meant they were killed by Jack the Ripper. When my nana died, her headstone had R.I.P on it. My parents hadn't told me she'd died of cancer, and I began yelling, 'But why would Jack the Ripper kill Nana?'