Just an idea that crossed my mind the other day:
We know at the moment that everything in the universe consists of either matter (electrons, planets, anti-matter) and fields (electromagnetic/gravitational/...).
Einstein noticed in his theory of Special Relativity that matter is equivalent to energy.
All fields are "distributions" of energy (the only interaction between a field and matter is energy exchange).
The Einstein equation E=MC2 defines the burn equivalency of mass and energy when matter converts to energy and vice versa. It does not say mass and energy are the same thing in all ways. The equation was needed to calculate the expected energy of nuclear bombs. It is like saying if we burn methane we can calculate how much energy we can get. This does not mean methane is the same as fire and heat. Beyond the energy/mass calculation there are some key differences between mass and energy.
Mass is invariant with frame of reference. Energy is the opposite and is variant with frame of reference. That is a huge difference. If we could change space-time around a block of mass and field of energy, the mass is not impacted, but the energy is. Mass is not dependent on space-time.
The physical geometry of mass can alter the local space-time. In a cloud of hydrogen space gas, space-time is not very contracted. As the mass collapses into a forming star, space-time will become more contracted around the mass, but the amount of mass does not change as space-time changes. It is not a two-way street like E=MC2. Mass is above space-time in hierarchy since mass is an absolute and space-time as much as space-time is dependent on mass.
If an object fell into a star, it is not the space-time well that will squish the matter. The squishing is connected to the pressure generated by the mass. Space-time does not generate pressure. The mass of the star is not only squishing the mass of the object, but it is also squishes space-time. The time of space-time will slow, while the object will undergo phase changes into faster time frequencies.
If we look at E=MC2 notice mass and speed of light C on one side. Both of these absolutes/invariants not dependent on reference. Energy, which change with space-time reference, and is variant, is all by itself on the other side. I would think that using two absolutes as the basis for physics would allow us to define the relative, but the other way around will not work since you cannot define absolutes like mass and speed of light using variables like space-time that has little impact on the absolutes.