Oatmilk:
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I could as well need some help regarding how those old texts are structured. ...
Theravada Buddhism is the oldest sect and has the oldest texts. They're structured into three 'baskets', one is rules for monastics, two for all the suttas, and three for the Abhidhamma. Within Theravada Buddhism there are further subdivisions, some teachers recognize the Vissudhimagga, and some don't (it was written long after the Buddha died).
The second basket - there are four big books called the Nikayas (these are what someone is usually referring to when they say "the suttas" in conversation), and there's a fifth Khuddaka Nikaya which contains collections of miscellaneous sayings. Here's a chart: https://readingfaithfully.org/simple-chart-of-the-sutta-pitaka/
I've only seen people reading the four main nikayas, and the Dhammapada, Ituvitaka and Udana. The other texts in the Khuddaka Nikaya are a bit obscure?
It's a noble goal to read the suttas, but they're prettty dry reading. I agree with what Martin posted, try "In the Buddha's words" as an intro before buying 40+ pounds of books.