I'm not very smart but I basically understand that string theory explains that everything is made of strings and there vibrations and interactions. I’m confused because aren’t there infinite ways to arrange the strings so wouldn’t there be infinite variations of the quarks, elctrons, neutrinos, bosons, etc.?
First of all, these are quantum strings, so the spectra are discrete. See this for more. Quantum strings have infinite possible ways to vibrate, but these ways differ by a finite amount of energy, the spacing between the spectra. These spacing is suppose to be very large if we compare with the energies per particle that we produce at the Large Hadron Collider (LHC). The particles that we know are suppose to be the ground state of these strings. A way to probe string theory is try to excitate the strings out of the ground state, but this require an absurd amount of energy for our current technology.