The question you asked is quite difficult, so I'll write a long answer. ^^
First of all, it can be really, really difficult for someone who has never coded in their life to study coding for the first time. Everyone has a different way of studying and understanding things. So, there is no right answer, and it's a very careful story to tell you what to do. I think that you don't succeed by reading the autobiographies of successful people and following their lives exactly. You have to change your own style to your own taste. This is my personal opinion, so please just refer to it. ^^
The lectures I gave actually cover a wide range of topics. The most important part of the lecture content is that if you understand all the Python grammar, the rest of the content is optional. When I was making the lectures, the most important thing I wanted to convey to beginners is that programming is fun! That's why I wanted them to think, "I want to make something too. Or, I can make something!" So, as you said, some codes are easy to understand, but some codes are not.
Whether you understand it or not, it is important to first follow the code and see the results. Of course, if you don't understand it, you won't be able to apply it later, so understanding it is important, but more importantly, finding what you enjoy and want to create is important. The ideas I come up with that way become weapons that can help me develop. I think it is much more important than listening to the lecture and understanding it first. It is not bad to understand it after becoming familiar with programming like this, and the most important thing is not to give up.
I think the most efficient way is to choose the most fun program that you can realistically create and write it from the beginning. Then, you will think about and think about what kind of logic the program you have in mind works, and you will know which field you need to study more deeply, and I recommend that you study one by one.
The commonality of people who do well on exams is that they find things that will appear on the exam and study efficiently, but people who do not do well on exams study the entire exam scope with equal weight. Of course, it would be nice to be smart and remember and understand everything, but most people, including me, do not. That is why, as I mentioned above, I keep emphasizing that you should start with the part that you really want to create. And if there are any parts of the course that you do not understand, you can actively utilize the Q&A bulletin board. ^^