We don’t. The Bible as a whole makes it clear how one is to live.
Besides, have you not read where Jesus says there are only two commandments? Do you think following two commandments requires a lot of picking and choosing among rules?
Those “two commandments” were in answer to the Jewish leaders trying to trip Him up.
He essentially said, in response to “what is the greatest commandment”, “the first four, followed closely by the last six”.
I’m curious as to why those two commandments exist in every religion, except those without a concept of God, which have only the second.