If you meet the Buddha on the road, tell him I said hi.

You haven't read much Abhidharma if "comprehensible" is how you would describe Theravada.

Not saying anything is wrong with Theravada. Entire cultures are built on its principles. But it takes a surface-level glance to think of it as something simple and easy to understand.

Zen though, most of the teachings are about pedagogical methods rather than doctrine. That's why it sounds weird to westerners who think of "religion" as dusty old books and priests who tell you what to do/think.

Zen teachings literally tell you "Don't cling to fixed ideas. Don't seek answers from some external authority figure." Everything they teach is about guiding you to internalize those things. It's about showing, not telling.

So expecting it to "make sense" in the lens of "just let me read a book that will tell me what to believe" is already starting from the wrong foot.

Rinzai Zen to be specific. Soto Zen doesnt emphasize koans.

Mahayana can be pretty out there too.

Siddhattha overhears these doubts being expressed so he takes of his clothes, spreads his legs and shows the ladies what is there - and what was there is his kosohitavatthaguyha glowing with a golden light. Then a lotus appeared and from its centre a baby boy’s penis emerges which gradually grows into an adult’s. More lotuses appear, each with a bodhisattva in it. The sutra doesn’t record what the ladies-in-waiting said about this extraordinary exhibition

https://sdhammika.blogspot.com/2010/08/strangest-sutra-of-them-all.html>