I've been debating with a friend about this.

I told him that space must exist since without it there's no superstructure that supports matter and makes it abide by some properties (triangle inequality, paths follow a geodesic, ...). Space even with the absence of matter is still a thing, it has properties like permittivity of free space, permeability of free space, curvature, ... Though I had to concede that our mathematical conception of space is only an approximation of real space.

But he was unconvinced and told me those are all human (social) constructs and they can't exist if we remove all humans from the planet.