Jerusalemite

Peace and blessings, I have a question about studying the Jerusalem Bible. From my impressions of it, it seems that the book is not particularly complicated. Probably because it was not attacked like the Babylonian Bible, it remained as it is. I wonder, would our ancient sages not have studied it as thoroughly as is customary? Even if they tell me that its depth is hidden and that it only seems simple, I am not willing to accept it without a convincing explanation.
It is clear that the Jerusalem Talmud briefly and simply explains the Mishnah, and brings in opinions from sages on laws. There is almost no debate, no room for argument, everything is simple. What does the rabbi think?
If so, and it is true that this is how the ancients taught, I see no reason to engage in such scrutiny.