Can someone explain the logic behind an Oral Torah?

Im fine with Rabbis having interpretation of the bible and following them. But Rabbinic Judaism claims that halacha laws are binding because they were given to us on Mt Sinai which is false and doesnt make sense.

Also some of the laws in the halacha just straight up go against gods word and the bible and some are using gods name in vain.

I just dont understand how can someone read the bible honestly and believe halacha laws do not directly oppose it.

Rabbinic Judaism to what ive see npersonally resembles Paganism way more than the Judaism god describes in the bible.

Sorry for the bad grammer, im from Israel and English is my 3rd language.