Is the Oral Law mainly of Divine origin or is it largely influenced by the rabbis/cultures of the time?

Do we now dismiss parts of the Oral Torah as incorrect?

For example scientific statements in the Talmud are nowadays largely ignored (things like flies moving the air around/lice coming from nowhere).

Does this take away from the holiness of the Oral Torah? Is it heretical to say that the Oral Law was influenced by the cultures of the time, for example with regards to women etc?