Once imitation gets good enough (general and accurate) were capable of spreading behaviors (phenotypes) without having to wait for folks to be born and grow up.
We don't really know what the upper bound for non humans is, because we don't know exactly what's being communicated by, for example, whale song.
It feels like bipedalism, opposable thumbs and strong social behaviour and other factores were the perfect storm at the perfect time.
For example monkeys have been known to exhibit fashion trends (hanging a bit of grass out of their ear). But these trends fizzle out over time. Before more behaviors can be layered on top.
I think you’re right about those factors creating a good environment for this to happen and I bet they’re sufficient but not necessary. Too bad we don’t have another example :)