Help me understand John Coltrane .... seriously.

I second other posts about listening to the Miles' albums first; also "Ballads."

Maybe even better would be "Duke Ellington and John Coltrane," the 1962 recording in which each of these great musicians gracefully gave up ground to meet the other in the middle. It might have been easier for Ellington, as he was a gifted accompaniest, able to comp virtually any other style of player. But Coltrane made his real gift apparent in the slower tunes, especially Strayhorn's "My Little Brown Book."

It's true that Coltrane developed a different language on his horn. But that's the norm in jazz...Parker, Gillespie, Armstrong, and any number of others had done the same thing in their time. To really hear what they're doing, listen to slow tunes; it's much easier there.

Coltrane as an artist exhibited more change over time than did most other artists (with the possible exception of Sun Ra).  Certainly much more than Miles.  A lot of people point to Miles as someone who constantly evolved, but his progression was always rooted in what was popular at the time.  Coltrane went beyond that.  Way beyond that.   From straight ahead player with Miles (and Monk), then his first baby steps as a leader, to coming into his own with his classic quartet, to his final sheets of sound/Free Jazz sound.   All different, but all from the same player.  

For someone looking to explore Coltrane, I would start with his work as a member of Miles's 1st classic group- all on Prestige.  Then to Blue Trane.  Then to his collaborations with Johnny Hartman and Duke Elllington.  This will take you from a player rooted in classic hard bop through his initial explorations in expanding standards.  Then take a deep breath if you want to go any further (and for some the above is enough). 

My Favorite Things shows the first manifest example of the direction Coltrane would take.  I consider the title track to be one of the first psychedelic jams, a harbinger of what was to come later in the decade.  His solo is like whirling dervish; in, around, ahead and behind the melody all at the same time.  Try listening through headphones, late at night-  this will probably be a vastly different experience than listening through speakers.   

If you want to continue, then jump into  A Love Supreme.  Know that this album was so influential that inspired the creation of a church congregation in San Francisco.   I'll admit I did not get this track for a long time, until I watched the Spike Lee movie 'Mo Better Blues".  This track plays over a climactic scene of a marriage taking place in twilight, on a Brooklyn rooftop, with lower Manhattan in the background.   The scene is beautifully filmed, with a late in the day technicolor feel to the film.  A Love Supreme is in perfect synchronization with the solemnity of the wedding ceremony, then the obvious joy of the celebrants.

If you are still interested enough to continue, then go for his free jazz titles that continued to push the boundaries of what was possible.

erik_squires here is an article aimed at the Coltrane-curious, like you with accompanying Spotify playlists: https://www.vice.com/en_ca/article/nemw88/john-coltrane-guide-essay-streaming.

As someone who loves everything about music but really is not educated in music in any way, Coltrane respect did not come until after years of exploring jazz. I started with Kenny Burrell and bought everything I could where he was sitting in. I could understand Kenny immediately it was several years before my untrained ear and my scrambled brain was able to hear the musical picture Coltrane was creating. The Coltrane documentary also helped me understand a little bit of what was going on with him as he was creating it. After 10 years of jazz exploration, Coleman Hawkins and Kenny Burrell are my go to’s over Miles Davis and Coltrane, although I understand the credit these gentlemen have and deserve. Just as Led Zeppelin or Pink Floyd pushed the bounds of rock, I rarely put them on for everyday listening. 

Coltrane typically modulates key changes differently than other Jazz players (major thirds). His progressions are often called “Coltrane changes”. Search for an explanation of “Coltrane changes” on YouTube and watch a video or two. After that, you’ll have a better idea of what’s going on in his music. With that understanding under your belt, the music should (hopefully) sound more accessible

Good luck