Relativity claims all is relative by observing all from a far. Quantum mechanics claims all is absolute by judging all particularly. String Theory claims that the most fundamental component(arche is the philosophical term) is vibrations.
There's no dichotomy between general relativity-a classical description of spacetime-and quantum mechanics, that describes the properties of matter within any given spacetime.
Relativity does NOT imply that ``all is relative"-it implies what the physically and msthematically well-defined quamtities can be. Quantum mechanics implies that these quantities must have well-defined probability distributions. The problem is that it isn't known how to compute the probability distributions when spacetime fluctuations can't be neglected.
Stting theory can answer one question, namely provide the probability distribution for quantum degrees of freedom that resolve the properties of certain black holes.
My hypothesis is that since human bodies decompose and spread across the universe after death that dead humans(if the soul and the body are the same) will find general relativity to be the only accurate way to observe for their dead selves. Assuming that consciousness is the energy within a human body then, that also leaves the body after death and then it may spread across literally everywhere(the known universe, the possible multiverse, and anywhere else that is possible) thus also making general relativity the most useful theory for those who have died.
Also found here on my Gettr account: https://gettr.com/post/p2qhjjq71cc