Could someone who is more familiar with physics explain something to me?

How is "the curvature of space" as an explanation for gravity not simply a metaphor for "the axiomatic force acts in the direction and proportionality of the mass of objects", which fixes some underlying/assumed 3 dimensional grid of distance while allowing its expression in reality to be morphed or altered?

Put another way: aren't those two things equivalent and why is one treated as more "real" than the other? Why is "curvature" talked about as if it's some fundamental reality rather than just a convenient metaphor for explaining the concept?