I agree with the conclusion. You mentioned social reality, but just to stress it even more, because I think the example with the rock might be a bit too simplistic in isolation. Historic materialism is not just practical but also dialectic and, well, historic.

So that notion of praxis is not isolated to one individual, one point in time and one stage in development. Marx (and Engels) innovative addition to materialism was not just to put it into individual praxis, but also into historic and societal context as well as to modify Hegels dialectic for this purpose and for even boarder applications. Historic materialist is dialectic materialism applied to the development of human societies.

Engels was delighted to see another application in evolutionary biology and Marx soon shared in his enthusiasm and wrote to Darwin to thank him.