No, space-time as we know it is a property of sense and cognition.
Think about a 3D first person game. As a player it appears as though we're walking through a 3D world, we can shoot things, bump into things, maybe drive some vehicles and so on. Now say we code an AI scientist as a character in this 3D world and give him the task of figuring out the reality of the world. He goes about and measures some things, figures out that there is "physics" involved when you bump into 3D objects and knock them over and so on. Then he starts exploring the boundaries of the map. He goes up to the very edge where the mountains and sky are and he finds out the mountain isn't actually a 3D object, it's just a flat image mapped onto a sphere to appear that way from a distance. When he gets really really close to the textures (images) mapped onto any of the 3D geometry he sees they start to become pixellated and really fuzzy. The naive 3D reality that he assumed at the beginning starts to break down and what he sees contradicts his original notions.
As humans we know that the fundamental nature of the AI scientist's reality is actually just some electrical signals passing through a CPU but that knowledge is completely inaccessible to the AI scientist. In the same way as humans we're in the very same predicament. We start with a naive notion of 3D space and as we explore the extremes things start to break down. At the QM level things get "fuzzy" just like the pixelated textures in the game world, at the cosmological scale we find that space is relatively flat and curved like the sphere surrounding the game world and cracks begin to appear - we can't reconcile what we see at the extremes with our original cognition and sense perception.
You are like the AI scientist in our game that is in the position of not ever being able to know the fundamental nature of reality but still you claim that it's a "thing out there" in-itself, it's "real". Yes, in a practical sense it is useful to consider that it is "real" because from an anthropocentric perspective it seems that way, so it is extremely useful to us to be able to predict behaviours and so on, but to make the leap to metaphysical materialism is a mistake epistemologically and by doing so you make assumptions that skew your understanding of other areas of human knowledge....such as mythology.
Spacetime and the chair both exist, irrespective of whether we are around to perceive their existence through our sensory organs. Our models of spacetime and the chair are simply approximations of their state, derived for our convenience. On the other hand, gods do not exist outside of the neural network patterns in the brains of theists, that we know of. Big difference.
There is more to gods and archetypal mythical figures than being merely ideas in the brains of theists. They are metaphorical descriptions of human behaviour and our psycho-social reality. The problem is that you are taking space-time to be an actual thing in itself, which it isn't and comparing that to mythology and using that as a basis to dismiss mythology.