Library of congress system is way too much for a home library, you occupy the categories so sparsely that it feels basically arbitrary. It is arguably like this even for small municipal and branch libraries.

Dewey is better but most people's personal libraries will be really heavy on a couple of the classes, light on another couple, the rest close to non-existent. So you still end up having to have a system to organize the class you have the most of, the dewey subclasses are still too fine-grained for a home library, and you have the LoC system problem again.

My spouse is a former librarian and we have a few thousand books between us, across a few rooms. What we do is each bookcase roughly corresponds to a dewey class or two, we try to avoid any one shelf having more than one subject. After that it's just by spine color. You'd be surprised how well this works! It's easy enough for kids to find and place books by color, and the visual sense memory works great for finding stuff. Every once in a while it'll throw you, "I swear this book was green" but whatever it mostly works.

Another thing that we don't do but could be fun is just to buy a set of the genre stickers that some libraries put on the spine.