On Facebook a guy was wondering about those who think this image does not show Jack Ruby. This is Jack Ruby but with incorrect aspect ratio he looks taller and thinner than Jack Ruby. So, some people can be convinced he's not Jack Ruby and are diverted off into a waste of time trying to find out who this guy really is.
Here's the same image but with the proper aspect ratio. Now when people see this image it's clearly Jack Ruby.
So, thank you to Philip Smith!