I addressed your incorrect understanding of the Torah in the above comment. God did declare Gentiles unclean in Ezra 6:21.

To bring up another misconception of yours, oral tradition was actually binding on the law abiding Jew, just as much as the written Law. Only, if the Oral tradition contradicted the written Law, the Jew was to question it and disregard it. In fact, Oral Tradition is actually encoded into the Law of Moses. How so? I'm glad you asked...

Deuteronomy 17:8-13 King James Version (KJV)
8 If there arise a matter too hard for thee in judgment, between blood and blood, between plea and plea, and between stroke and stroke, being matters of controversy within thy gates: then shalt thou arise, and get thee up into the place which the LORD thy God shall choose;
9 And thou shalt come unto the priests the Levites, and unto the judge that shall be in those days, and enquire; and they shall shew thee the sentence of judgment:
10 And thou shalt do according to the sentence, which they of that place which the LORD shall choose shall shew thee; and thou shalt observe to do according to all that they inform thee:
11 According to the sentence of the law which they shall teach thee, and according to the judgment which they shall tell thee, thou shalt do: thou shalt not decline from the sentence which they shall shew thee, to the right hand, nor to the left.
12 And the man that will do presumptuously, and will not hearken unto the priest that standeth to minister there before the LORD thy God, or unto the judge, even that man shall die: and thou shalt put away the evil from Israel.
13 And all the people shall hear, and fear, and do no more presumptuously.

and again...

Matthew 23 King James Version (KJV)
23 Then spake Jesus to the multitude, and to his disciples,
2 Saying The scribes and the Pharisees sit in Moses' seat:
3 All therefore whatsoever they bid you observe, that observe and do; but do not ye after their works: for they say, and do not.
4 For they bind heavy burdens and grievous to be borne, and lay them on men's shoulders; but they themselves will not move them with one of their fingers.

Now, you can say that when they are in Moses Seat, they are reading the prescribed portion of the Torah, so they are actually hearing the written Law read. That sounds like a plausible answer, but the very fact that the Moses Seat is referenced and from where this seat was located is all based on "oral tradition" and not founded in the Torah itself. Correct me if I am wrong, but the "synagogue" was not ever commanded or described in the Torah to be a place of worship, nor were the ceremonies and procedures of the synagogue ever described or commanded in the Torah. The synagogue and the activities of it are all based on "oral tradition" of High Priests and Rabbis. Correct me if I am wrong again, but the "Moses Seat" was never mentioned in the Torah either. The closest you can get to any mention of it is Exodus 18 where Moses sat to judge the Nation of Israel. His father-in-law, Jethro, advised him to appoint Judges who would be "rulers..."

Exodus 18:14-27 King James Version (KJV)
14 And when Moses' father in law saw all that he did to the people, he said, What is this thing that thou doest to the people? why sittest thou thyself alone, and all the people stand by thee from morning unto even?

15 And Moses said unto his father in law, Because the people come unto me to enquire of God:
16 When they have a matter, they come unto me; and I judge between one and another, and I do make them know the statutes of God, and his laws.
17 And Moses' father in law said unto him, The thing that thou doest is not good.
18 Thou wilt surely wear away, both thou, and this people that is with thee: for this thing is too heavy for thee; thou art not able to perform it thyself alone.
19 Hearken now unto my voice, I will give thee counsel, and God shall be with thee: Be thou for the people to God-ward, that thou mayest bring the causes unto God:
20 And thou shalt teach them ordinances and laws, and shalt shew them the way wherein they must walk, and the work that they must do.
21 Moreover thou shalt provide out of all the people able men, such as fear God, men of truth, hating covetousness; and place such over them, to be rulers of thousands, and rulers of hundreds, rulers of fifties, and rulers of tens:
22 And let them judge the people at all seasons: and it shall be, that every great matter they shall bring unto thee, but every small matter they shall judge: so shall it be easier for thyself, and they shall bear the burden with thee.
23 If thou shalt do this thing, and God command thee so, then thou shalt be able to endure, and all this people shall also go to their place in peace.
24 So Moses hearkened to the voice of his father in law, and did all that he had said.
25 And Moses chose able men out of all Israel, and made them heads over the people, rulers of thousands, rulers of hundreds, rulers of fifties, and rulers of tens.
26 And they judged the people at all seasons: the hard causes they brought unto Moses, but every small matter they judged themselves.
27 And Moses let his father in law depart; and he went his way into his own land.

Having said all that, Jesus condemned the Pharisees and teachers of the Law when what they taught contradicted the written Torah, but he commanded them to "observe all that they say" in keeping with Deut. 17 in Matthew 23:3. If there were circumstances that were too hard to understand how to obey according to the Law, God had Priests and Judges, legislate for him. This system is where the oral tradition comes in. If the commandment says you should do no work on the Sabbath (Lev 23:3) There are natural questions that a God fearing person would ask? What constitutes work? How far can I walk and not be caught working? How much am I allowed to carry, if anything? These questions would be asked and the priests and judges would give their interpretation of how they best understood to obey the Law. Those understandings became binding upon the hearers. They were then encoded into extra biblical writings such as the Talmud.

From my understanding, Law begets more Law, when one is seeking to be made righteous by following it. If the heart isn't right from a licentious point of view, the question invariably always is "how close can I come to breaking the Law without actually breaking it?" On the converse, the heart that isn't right from a self-righteous point of view, the question invariably always is "if a little of a law is good, then wouldn't a lot of that Law be even better." And they begin to add more stipulations and nuances of understanding to the Law to make sure full obedience and compliance is met.