What am I missing? And I mean that as in, what can I listen to, that will help me see what others see?
What might be a better place to start would be the cello suites. The first is so well known that it's hard to come to it with an open mind. But my favorite is the second in d minor. Here is a performance by Mischa Maisky: https://www.youtube.com/watch?v=ki9ySiWQNu8 Much more lyrical and passionate than we often associate with Baroque music.
Bach is, of course, very well known for his counterpoint, which probably is why a lot of technical people like his music so much. I personally like these pieces best on organ. The fugues in particular are always a great deal of fun as each line comes in and the piece gets richer and richer. Here is a performance of the Great Fugue in G major: https://www.youtube.com/watch?v=6clTa8_QYQE I think there's really no substitute for listening to these pieces live, though. With a good organ you just get enveloped in the sound. The next best thing to do is wear good headphones and really crank up the volume, but headphones just can't match the bass of 64 foot pipes.
I'd also be remiss if I didn't mention the Chaconne from his partita for violin: https://www.youtube.com/watch?v=HEbi-7tPaqo
Anyway, what I really like about Bach is how much many of his compositions just swing. He was a big fan of the canon, where a melody is played simultaneously by several voices/instruments, but with an offset and counterpoints. He uses this to create what to me are beautiful textures and great rhythm.
Not sure classical music generally is much slower or faster than "modern" music (there is of course a wide variety in both), but I would say, also generally, that a classical piece is harder to learn to play because it tends to have a more complex structure and is less repetitive than most contemporary pieces.
(This is not a slight against modern music; personally, I enjoy listening to both classical and modern.)
I remember as a teenager listening to Mozart and thinking "this is slow and boring", while Metallica is "super fast and cool", when in actuality the Mozart piece has a faster tempo and many, many more notes produced per minute.
Not a dig on Metallica, I still enjoy their music, just that my horizons have broadened.
https://www.chenalexander.com/Bach
It's not for everyone and that's fine. I have some suggestions to try though.
BWV 999
https://www.youtube.com/watch?v=0g4FrGcRAIs
Goldberg Variations #13
https://www.youtube.com/watch?v=q5-7QENoXoA
Erbarme dich, mein Gott
https://www.youtube.com/watch?v=Zry9dpM1_n4
Cello Suite #6 Sarabande
https://www.youtube.com/watch?v=qzb8aEW_Rdc
I'm going to go a little rogue with the Chaconne and suggest an arrangement ...
Bach: Harpsichord Concerto No.1 in D Minor BWV 1052 (Jean Rondeau)* I'm sure some people will hate on this unorthodox interpretation, but to me this is sublime.
https://www.youtube.com/watch?v=XcsfDxojdV8
Johann Sebastian Bach - Chaconne, Partita No. 2 BWV 1004 | Hilary Hahn * The solo violin bible
Cello suites. See No. 6:
* https://www.youtube.com/watch?v=wbH3JYfRjOQ
Violin concertos; e.g., D minor:
* https://www.youtube.com/watch?v=bZFOhkGGr8A
Brandenburgs:
I guess his slow chorales are played the most in churches and ads. but he composed so much more. Some of my favorites are The Well-Tempered Clavier, Goldberg Variations, and English/Italian Suites.
Here is some slow, boring but not religious stuff, no hapsi and no singing:
js bach, the art of the fugue
https://youtube.com/playlist?list=PL5BC3686A00C91558
it was a demo of the gist of his composition, his music making: he introduces a melody, the motif, and then overlays it with itself and variants of itself and I admit the details completely escape me.
yet the music captures me and allows me to think.
I found it surprising nobody yet mentioned the “Gödel, Escher, Bach” book by Douglas Hofstadter. Not sure how popular the work is today, but some years ago it was really famous.
I read the book years ago, and loved it. Learning about Gödel's incompleteness theorems had already my blown my mind; Escher already was, and still is, my favorite visual artist. I remember well, at a general level, the book's explanations of counterpoint, constraints, and logic in Bach's compositions. In stark contrast to the rest of the book's content, that was all somewhat academic since the book didn't play any music.
Ever since reading the book, it has greatly saddened me to think about how much enjoyment I get from the work of Gödel and Escher, and that I'm missing out on the third component of Hofstadter's holy trinity of self-reference.