Philosopher,
What is relevant is whether it was the Tzedoikim, the Early Christians who were Jews, or the Christians and Messianic “Jews” today, the Keruim, Shabsi Tzvi and his followers, and all kinds of groups in history who tried/try to prove from Torah sources that their beliefs are true
Actually, they used pesukim to prove that תורה שבעל פה is false ch”v, exactly as YOU have done!
I, in the other hand, am defending the holy meforshim of תורה שבעל פה.