Garden Toys - Ideas Please!

We live in the UK, our kids are 1 and 3 years old. The kids have toys but not really much in the garden. The neighbours have climbing frames and sand pits but tell me they don’t get used a lot and just clutter and rot away. What have been your biggest wins for the garden?

I recently bought a sports day set, cones and bean bags etc, which was a hit, and they love making houses out of empty cardboard boxes - but I feel like I need to up my game a bit.