I think the concept that they were not as ‘intelligent’ as ‘we’ are, is a mistake of modern culture.
There could be other reasons for men in prehistoric times constructing a cobblestone path. Basically the same reasons ‘modern’ men do.
I think men can do, and have always done, anything they chose. What they chose to do depends on the environment they have to live in.
They built this prehistoric path, because they needed it, or because it looked nice in their yard.
Fewer environmental regulations then. I'm thinking they didn't have some bureaucrat harping on them about the impermeability of the pavement and how that the runoff was bad for the fish.