The conceptual model of multidimensional vibrating strings provides an incredibly rich and diverse "language" that almost certainly is encompassing all of known physics as a singular point somewhere within its almost unfathomably large parameter space; e.g. see What experiment would disprove string theory?.
However, since in our human-sized world the fundamental organizing concept of "vibrating strings" comes to us from observing complex, multilevel interactions of condensed matter, and fields within space and time (e.g. see What are the strings in string theory made of?), another possible interpretation for this compatibility exists.
Perhaps the inclusiveness of string theory emerges not from the simplicity of vibrations, but from the mathematics of vibrations being some sort of beautifully succinct emergent expression of of the many diverse physics threads that must come together to create a universe rich enough for both observers and string-like vibrations to exist within it. If so, string vibrations would be more like the outer crystalline facets of some incredibly rich and complex compound, or perhaps the mouth of Krishna: An outward expression of seemingly simplicity within which the entire universe lies hidden.
So, after all of that, my question is this: If the all-inclusiveness power of string theory is emergent rather than primary -- that is, if any working string vibration model already contains all of known physics, even if in redundant or highly distorted form -- then shouldn't there exist experimentally tractable methods by which the quality of diverse string models and string model categories can be compared and selected? Such selections would be based on a sort of Occam's razor or signal extraction approach that seeks to minimize their complexity and maximize their fit to known physics, I would think. (I may elaborate more on that later; it's late.)