One of the biggest problems families have living in a small space is all the stuff kids have that seems to grow all by itself if you don’t constantly cull.
Try doing regular sweep through the house. Maybe every month or 2. Put every toy or craft item you haven’t seen anyone play with in a while away in an out of the way place like the garage or basement.
If the kids don’t notice after another few weeks, send it off for donation or into the garbage bin.