Marcel,
I see meters as a measure of distance, which is a quantity of space. I see seconds as a measure of action, which is motion in space. Meters grow longer when they are composed of matter that expands. Like water does when it's heated. Seconds are longer if the action being measured slows.
If you heat something up, it expands, but the action speeds up, as well, so longer distance+faster action=C.
Now if you put this matter under enormous pressure, like way down in the planet, it will get hot, but it isn't expanding, because the pressure is putting the same amount of matter and thus energy, in a smaller space, so temperature goes up. Aka ideal gas laws. Basically volume and temperature are correlated. Squeeze the volume and pressure pushes up the temperature. Just like acceleration correlates measures of distance and duration, aka spacetime(actually only one dimension of space), as velocity compresses mass and slows light/action. So the time/duration the light takes to travel the distance is Constant.
Gravity is presumed to be Equivalent to acceleration, thus velocity, aka the Equivalency principle. So its called spacetime, but it is the relationship of action to space. There is no time dimension, like there is a s[ace dimension, as the energy manifesting the action is only present, aka conserved. As in always and only present. Duration is the present, as events coalesce and dissolve, go future to past.
Not sure if this is any more convincing. It's late and my brain is barely turning over.