I recommend "Dropping Ashes on the Buddha" (just search on Amazon) which is a collection of talks the founder gave while teaching in the 70's ... it's very simple and not 'facts about religion' but Zen in daily practice - how to clear your mind, what's the nature of the mind, what's the nature of reality, how our mistakes about that nature cause us and others suffering. You can read it in 2 page increments ... it's not factual ... it's interactions with students.
https://cambridgezen.org/
The Buddha so far as I have seen, and if you don't accept the junk that's been piled on it or the left interpretations, was correct about everything. He also said 'If you don't experience what I am teaching as true, then throw it out.'
I know that many here, especially traditional Christians, often find Buddhism to be awful and bad and evil. They may only have contact with perverted versions of it, i.e. not original scripts. You have to be careful with Eastern stuff, not because in itself it's bad ... just that ... you have to go to the source. Just like there are a ton of fake Christian's peddling falsehood, same with Buddhism which has unfortunately been embraced most strongly by the left.
What I like most about Buddhism is that it seems kind and it contains much common sense. I catch flies and take them outside. A reverence for life is central to my world philosophy. I’m awed by the spark of life that appears in every creature, people just being one example.
Understand what you mean about added fluff. And I do like going direct to (translated) sources. U of Chicago was big on teaching from original sources. The only texts we had were in math and physics and chemistry, as I remember. Other than that, we had collected papers to study Mendel and such. I still have all my old collections of Greek and Roman philosophers from Western Civ.
Buddhism is a philosophy, not a religion, and a noble, humane philosophy at that. We should fully expect that its best insights, correctly understood, are compatible with Christianity, correctly understood. The same can be said of the classical Greek and Roman philosophical tradition, which brings us straightaway to the Rome & Jerusalem synthesis.
What the Buddha taught was not religion. Most practicing native Buddhists do not meditate and don't practice. The religion is more cultural baggage than it is Buddhist practice.
What the Buddha actually taught is the most profound and true ancient wisdom we have, mostly because it's entirely focused on something real. Our minds.
I highly recommend this new book, which relates Buddhist teaching to modern psychology.
: https://www.amazon.com/Why-Buddhism-True-Philosophy-Enlightenment/dp/1439195455