30) If the Bible is as clear as Martin Luther claimed, why was he the first one to interpret it the way he did and why was he frustrated at the end of his life that “there are now as many doctrines as there are heads”?
Because men are fallible and sinful.
1) I'm quite sure Steve Ray cannot give an accurate citation for that alleged quotation from Luther. The quotation appears to be taken from a translation/paraphrase by Joseph Lortz. Lortz provides two translations/paraphrases:
The whole history of philosophy and religion, of Christian heresies, and finally of the Reformation itself, is convincing proof of a statement that Luther himself affirmed in his First Lecture on the Psalms: “Unless doctrine is authoritatively promulgated by a living human being endowed with the authority to teach, there will be as many doctrines as there are heads.”Joseph Lortz, The Reformation: a problem for today (Newman Press, 1964), p. 246
In his lecture on the Psalms (about 1512), he had said: “Unless doctrine can be authoritatively guaranteed by one living man, there will be as many doctrines as there are men.”Joseph Lortz, The Reformation: a problem for today (Newman Press, 1964), p. 149
(Lortz's German is the same in both cases: "Wenn nicht im Lehramt durch einen lebendigen Menschen die Lehre verbindlich verkündet wird, wird es so viele Lehren als Köpfe geben.")
Notice in particular that 1512 is about five years before October 31, 1517, the famous date on which Luther posted his ninety-five theses on the door of Wittenburg Chapel. In other words, this is not a quotation from Luther at the very end of his life, but from Luther before he had even come to oppose publicly the sale of indulgences by the mechanism of the 95 theses.
2) On many important things, like sola fide and sola scriptura, Luther was not the first one to interpret Scripture as he did.
3) The Reformed doctrine of perspicuity (see some standard definitions here) does not claim that Scripture is so clear that everyone who looks at it comes to the same conclusion with respect to every doctrine.