Leviticus, speaks of one of the Rebellious Watcher/Angels/Demon and uses specific Same Name as Enoch uses in his Tradition:
AZAZEL
From Book of Enoch:
Azazel is the rebellious angel at the head of a heavenly plot to take over the earth. The First Book of Enoch retells the story cited in Genesis (6, 1–4) of the angels who had relations with the daughters of men. The offspring of their unnatural union were the nefilim—giants of renown who filled the earth.
From the Torah/the LAW:
Azazel is one of the leaders of the rebellious Watchers in the time preceding the Flood; he taught men the art of warfare, of making swords, knives, shields, and coats of mail, and taught women the art of deception by ornamenting the body, dyeing the hair, and painting the face and the eyebrows, and also revealed .
And here are some Verses with God addressing Moses about AZAZEL:
Leviticus 16:
8 and he shall place lots upon the two goats, one marked for יהוה and the other marked for Azazel.
9 Aaron shall bring forward the goat designated by lot for יהוה, which he is to offer as a sin offering;
10 while the goat designated by lot for Azazel shall be left standing alive before יהוה, to make expiation with it and to send it off to the wilderness for Azazel.
In Ancient Hebrew Tradition, the Demon LILITH is specifically mentioned by the Prophet Isaiah:
Isaiah 34:
Wildcats shall meet hyenas,
Demons shall greet each other;
There too the lilith shall repose
And find herself a resting place.
Deuteronomy tells us of People who sacrificed to Demons:
32:
They sacrificed to demons, no-gods,
gods they had never known
There's other examples, but as you plainly can read, Demons, were common knowledge at least since Enoch, Genesis Chapter 6.