Help me understand John Coltrane .... seriously.

Erik, 

I love jazz and I don’t love Coltrane. I respect him and like some of his work. Overall, I find his lead lines stabbing, terse and not very melodic. He often sounds like he’s racing through scales and modes. I’m with you. 
When I was first exploring jazz 25 years ago I listened to him because he’s in the cannon of popular jazz. Today, I’m down to owning just two of his albums and I rarely play them. 

I recommend picking up a copy of Ted Gioia's book, "How to Listen to Jazz." I've been a jazz fan for decades, but I still found this book helpful and enlightening.

It's not dense, very readable. As you can tell from the title, it's written for the everyman and it not technical.

https://www.amazon.com/How-Listen-Jazz-Ted-Gioia/dp/0465093493/

Hey I don't get Rap "music", it doesn't bother me in the least.  If you do not like bop or post bop jazz, so what?   It does not make any sense to some people. Others can recognize the structure in the improvising.  They play the notes in the chords around the melody. It is like algebra instead of arithmetic.  Oh they know ALL the rules, and know how to break them. It is not totally random the notes they play. 

Help me understand ART .... seriously.

That is what you are really asking because real jazz is art. And as with any art form it is ok if you don't get all of it or appreciate all of it, as long as you try. Just move on to another artist and come back to it latter. The more you listen to jazz the more you will find yourself gong back and appreciating pieces you previously passed on.

But of all the jazz artists, I'd have to admit that JC is one of the more difficult to "get" and best left for serious listening after one has a better understanding of jazz.

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.