"He was a giant of neoclassicism and writing original music in basically a sort of refurbished style to make his own style." what makes him different from Stravinsky or Ravel?
"He wrote many different types of works and forms, symphonies, concertos for many different instruments, operas, ballets etc." It is significant. Every good composer did that. But I'm not sure this renders a composer canonical though.
"He could imbue a type of character into his pieces that no one else could." Yes. What character did he produce that others could not? Orgiastic and full of frenzy for example his 1st violin concerto scherzo? Well Rite of Spring could do it. (that isn't to say that being able to reproduce a character that others happened to have done before reduces the value of his art).
"Combine lyricism with sarcasm, drama with soaring melodies". Question of interest: what actually makes his music sound, as many people put it, 'sarcastic'?
1. Ravel was impressionist so I don't see your point. Sure Stravinsky was important for neoclassicism too but he's different to Prokofiev. Stravinsky was more explorative and daring, Prokofiev more on the melodramatic side, exploring a wider range of emotions etc. Personal preference is personal preference here
2. Sure but the large catalogue of works is in this new style. He's not a Mendelssohn who doesn't break barriers or a Chopin who only wrote for one instrument, so yes the fact he produced many different works is important (not to say Chopin and Mendelssohn arent goated either)
3. Its quite brash to say Rite of Spring is an emulation of the 2nd mvt of the violin concerto. Theyre very different, Rite of Spring has a primal character, almost savage, and the rhythms and harmonies reflect that. Prokofiev's liveliness still contains elegance and is undoubtedly innovated. Having played both, the techniques required are completely different too, so yes Prokofiev's character is quite unique (so is Stravinsky's)
4. Chromatic displacements, unorthodox harmonic progressions, ironic orchestrations, all the while often with a lyrical soaring melodic line. That lends itself quite nicely to sarcasm