The prevalence of the Torah, and the Torah during the First Temple period

B.E.
Hello Rabbi Michi,
I wanted to ask what you think about the igod question, from part 10:
There is a question that sees a break in tradition at the time of Isaiah, and we encounter this a few other times in the Bible, although it does not seem likely to me that the intention is that they forgot the actual Exodus from Egypt or the presence of Mount Sinai, and since the Torah scroll itself was found, it is reasonable to assume that they knew in advance what to expect and were familiar with the Mishrah.
But it still means that they forgot parts of the commandments as it says there (maybe Passover?). And if so, can we say that there was a disconnect with regard to the Oral Torah? That is, if indeed they did not keep such basic commandments, then we cannot trust the concept of “Oral Torah,” because the sages were not given the authority to study the Torah, as it does not seem that they were too concerned with matters of the Torah in their time.
2. Also, how does the Rabbi understand the words of Chazal about studying Torah during the First Temple period, as, for example, in the time of Hezekiah it is said that they did not find a baby or a baby boy, a man or a woman who were not versed in the laws of impurity and purity?
And as the sages explain, the halakhic negotiations between Moses and Aaron regarding the scapegoat that Moses demanded.
And so with regard to Othnael ben Kenaz in Philopello, etc.
How does the rabbi understand all these sayings? Is it literally true or did they come to express another idea, and what is it? Is this an “anachronistic” reading of the Bible?