Help me understand John Coltrane .... seriously.

Please listen to "Theme For Ernie", "Body And Soul" and "My Favorite Things" that will make him easy to step into or forgetaboutit. Duke Ellington & John Coltrane "In a sentimental mood" also a singular gem.

John Coltrane for many is quintessential.

Oh, and @dekay I think these guys nailed the cover of KG's Giant Steps...

https://www.youtube.com/watch?v=djHXUEUTA-0

+1 on Ballads. 

I have a friend who is a huge music fan. I was shocked when he told me he hated Miles Davis. Apparently, years ago his uncle, an accomplished Jazz pianist, had given him a copy of "Bitches Brew" to add to his collection of classic rock albums.  Starting Miles with "Bitches Brew" is like introducing someone to rock music with Nine Inch Nails. There is no way they could get it. They would need to start with Elvis, The Beatles, Cream, Led Zeppelin...

I suggested he listen to Kind of Blue and go from there. 
If you are new to discovering Jazz, I suggest starting with Lewis Armstrong, then follow the trail of musicians influenced by him.

And Ah
On Coltrane '58: The Prestige Recordings "Lush Life" and "I want to talk about you". They are on Qobuz 

On Coltrane Plays The Blues try the iconic "Mr. Syms" (on Qobuz too).

Then pease listen to all of these albums or if not for you then chacun à son goût and hasta la vista señor.