That's really sad that everything was thrown out. You will be surprised what you can find about an ancestor's life. I started with just my dad's birth certificate and now have 4 Lever Arch files on him and his family.
Definitely keep photos of family members, with names on the back and when and where taken if possible. Also photos of family homes, otherwise throw out holiday snaps, animals and views, no-one will want them. Letters and postcards can be interesting, I have a whole suitcase full (from 1930s) but really must reduce them!