As a kid I enjoyed the Rubik snake which I could contort into interesting patterns. My brother who was a few years older had a few other cubes, such as some with many more angled faces etc.

As for cooperative invention, it would seem that humans are not as unique as we think we are. In exactly the same way we have doppelgangers that look like we do, we also have people that overlap with us in behaviour, personality and ideas. Side by side invention is just one facet of that.