I will offer a simpler, and somewhat philosophical explication of what, I believe, Superstring theory represents. It also causes me to be convinced that the basic idea of the theory pretty much has to be right!
At base, I think it represents the resolution of a confusion about the relationship of mathematics to physics. Physics requires some physical extension in "reality"; whereas math is pure theory. In math, one commonly utilizes the idea of dimensionless points. Physics, which is so used to importing ideas from math, seems to have forgotten the philosophical difference between the 2 disciplines. It began utilizing the idea of "point-particles" ---which were conceived of as "dimensionless"; i.e. without physical extension. To my mind, with Superstring theory physicists (through extremely difficult mathematics) finally "came to their senses".
Physics is a discipline, unlike mathematics, where some physical extension is absolutely necessary. Thus, it was never possible that there could have been such thing as "dimensionless" "point" particles. Though subatomic "particles" are conceived to be the smallest possible "things", they still need to have some physical extension in order to "exist" in "reality". Superstring Theory, philosophically, recognizes that the smallest possible physical extension must be a one-dimensional entity (once you accept that "dimensionless" cannot be a physics construct, there must be at least one physical dimension in play). Yet, of course, the most basic physical entity must also be the "smallest possible" one-dimensional entity.
Now, most people would believe that there is no such thing as the smallest possible thing. One would logically assume that "you can always cut it in half" and get something smaller. This logical assumption is very similar to the belief that, however fast something is moving, it can always go a little faster. Einstein proved, at the time shockingly, that the latter assumption was wrong. You cannot always go a little faster. The universe has a "speed limit", and nothing can ever accelerate to the speed of light. Yet few people realize that, just like the false assumption about speed, so our assumption that there is no limit to smallness is also wrong.
All physicists realize that the is a limit to smallness ---it is called Planck Length. So, at last, we can reasonably talk about "least possible physical extension" as a meaningful physics construct replacing the construct of "dimensionless" mistakenly imported from mathematics. The simplest physics entity that could ever "exist" would be a one-dimensional entity of Planck Length. Is it, then, surprising that this turns out to be the very definition of a Superstring?
Lo and behold, when the universe is viewed in terms of this simplest of all physical construct, we see the very term "particle" becomes replaced by the more accurate metaphor "string". Then we suddenly see that the vast "zoo" of physics entities formerly called "particles" are understood as Superstrings vibrating differently in 6 dimensions (within a larger 11 dimensional hyperspace).
As has been said often, each different string vibration is like a different musical note. Like one guitar string can create a B flat, an F#, or a myriad of other notes; so each superstring can vibrate to create of create a myriad of subatomic structures ---photons, electrons, neutrinos, gravitons, etc.
Anyways, that's the simple way I think of Superstring Theory such that it seems to me so obviously right.
