Buddhist objective is nibbāna, the safest, so the reader need to learn it hard step by step

Buddhist objective is nibbāna, the safest.
It's like the science's, engineering's or computer programming's rule, we can't misunderstand at any level of the process. It's buggy, risk and unsafe.
Therefore, it's very hard to understand Tipitaka and Atthakatha as alike as science's, engineering's or computer programming's rule.
So, if you point your expectation in Buddhism only at the easy part, you will miss the safest part, which elaborated multi aspects of reasons. That missing is buggy, risk and unsafe.
So, concrete exposition of Buddhism is the conclusion like:

1. Vinaya is in VN Parivāra by upāli, the vinaya secretary of buddha.
2. Sutta is in KN Paṭisambhidāmagga by sāriputta, the stand-in teacher of buddha in MN Mahāgosiṅgasālasutta (or alternative in translated Visuddhimagga but if you bias of the supernatural, it's not your choice).

Both above require these to understand:

1. Pāli skill from Kaccāyana.
2. Tipitaka analysis skill from Netti.
3. The discipline of everything from abhidhamma by sāriputta, the stand-in teacher of buddha in MN Mahāgosiṅgasālasutta. Or, saṅgaha by anuruddha, past laṅkā's pontiff.

But if you want to start in Buddhism, you need:

1. Qualified teacher to teach you step by step.
2. Easy sutta to recite and do follow, such as Maṅgalasutta (and all Khuddakapātha), Siṅgālakasutta, and dhammapatha.