So I’m an insurance agent who has also been through a house fire personally. Any of the options people have suggested here would be fantastic and far better than what most people have, which is nothing.
What I suggest to my clients is to make a video once or twice a year walking through your house, inside and out. Video makes it less likely to miss a small detail that turns out to be important later than pictures, but pictures are also helpful. Insurance aside, it’s kinda fun to look back and see how things have changed through the years. I like to do it around Christmas.
Ideally that would be in addition to a spreadsheet or something with receipts and serial numbers and individual photos of specific items, but that’s a lot of work and hardly anyone keeps up with it on a consistent and long-term basis.
Whatever you end up doing, it’s useless if the only copy is stolen, burned, or sprayed with a hose. This is one thing I keep with a major cloud provider with a local backup. At the very least, make sure you have an off-site backup that’s reasonably up to date.
I use Futurama-based names. It started with my wifi network, which I named Zoidberg, because why not. The NAS is Infosphere, the media server is Hypnotoad, etc.