Since ancient times, many great calligraphers can't write regular script at all. There is a specialization in the art, not every calligrapher can write regular script, and there is no necessary causal relationship between regular script, cursive script and official script. When we look at the history of calligraphy from a historical and objective perspective, we will forget that regular script is not necessary for getting started.
So can we just start with cursive script? Personally, I think it is not impossible. However, I still think that if you really want to be a calligrapher, it is better to start with official books (Kai, Zhuan and Li). Because this kind of formal book is formal in style, independent in strokes, stable in structure and easy to be mastered by beginners. For example, some famous calligraphy majors in the Academy of Fine Arts are mainly seal script, and some colleges are mainly official script. Now, we should also see that many calligraphy professional examinations basically relaxed the regular script style before the Tang Dynasty, even in Wei Bei.
There is no difference in the five calligraphy styles of Zhengcaoli seal script, and regular script is not a low-level calligraphy style. On the contrary, writing regular script is more difficult than writing cursive script. The calligraphy style of beginners is nothing more than training and copying, so that beginners can master the control ability and modeling ability of using pens.
If you want to start learning calligraphy, I don't suggest you start with it, especially Yan.