Welcome to the Community,
I think you are mixing up shared storage for the ESXi host and shared storage for VMs. With ESXi you create virtual machines with virtual disks which are basically files on a datastore (shared or local). If you configure separate virtual disks (e.g. for OS and data) you could attach the data disk to another VM if the original on breaks. However, whether it is possible to share the virtual disks between the guests (i.e. access them simultaneously) mainly depends on the guest operating systems capabilities. Most operating system do not allow this and doing it anyway would most likely cause data corruption in the guest's file system.
André