Data is easily saved by uploading to cloud storage, preferably more than one service. You should already be doing this, Google Drive is 15GB free, Dropbox is 2GB free. Usually that's enough for the most important documents. Google Photos has unlimited storage as long as your pictures are 16MP or less.
I'll admit that I don't have an overview of my irreplaceable items. Maybe I should do a mental list when I get home today.
A few years back I scanned all of our personal records, tax returns, visas, dog vaccinations etc and created a dedicated Box account with a Google Drive backup. It was a massive undertaking at the time, but now whenever we receive something new it's a pretty painless task to scan it and upload it to cloud storage.
An added bonus is that after years of stockpiling paper we now have virtually no paper records anymore other than the things that absolutely have to be: passports, SSNs, birth certificates etc.