You can't make this stuff up, folks. Rabbi Shraga Simmons writes on Aish.com:
Amazingly, that day at Sinai was the first time the Jews ate dairy products. There is a general prohibition of "eating a limb from a live animal" (ever min hachai), which logically should also include milk, the product of a live animal. Ever min hachai is actually one of the Seven Noahide Laws which the Jews observed prior to Sinai (and which has applied to all humanity since the days of Noah).
However, upon receiving the Torah, which refers to the Land of Israel as "flowing with milk and honey" (Exodus 3:18), dairy products became permitted to the Jews. In other words, at the same moment that their meat became prohibited, dairy became permitted. They ate dairy on that original Shavuot, and we do today, too.
Now, let us compare this with an actual series of verses from the Torah:
And the LORD appeared unto him in the plains of Mamre: and he sat in the tent door in the heat of the day; And he lift up his eyes and looked, and, lo, three men stood by him: and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground, And said, My Lord, if now I have found favour in thy sight, pass not away, I pray thee, from thy servant: Let a little water, I pray you, be fetched, and wash your feet, and rest yourselves under the tree: And I will fetch a morsel of bread, and comfort ye your hearts; after that ye shall pass on: for therefore are ye come to your servant. And they said, So do, as thou hast said. And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth. And Abraham ran unto the herd, and fetched a calf tender and good, and gave it unto a young man; and he hasted to dress it. And he took butter, and milk, and the calf which he had dressed, and set it before them; and he stood by them under the tree, and they did eat. And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent. And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.
To believe Hebrews did not eat milk or dairy products (or eggs, because eggs are also "ever min hachai") is on its face insane. To believe this when a specific biblical verse contradicts it is simply stupid.*
Aibishter, look what these rabbis have done to your Judaism!
*And do not try to say that Avraham merely prepared the food for the "men" – who were not keeping the halakhot of bnai noach – to eat. Avraham would be forbidden to do so under any normative understanding of halakha. Plus, this assertion is itself foolish.