So, like many people, have completely not understood how this bible and Christianity thing works.

The ten commandments, together with the other laws of Exodus and Deuteronomy, are part of the old covenant. The key thing of Christianity is that Jesus set up a new covenant, replacing the old with the simple formula “love thy neighbor like thyself”. The old ten commandments (at least 4-10) can be seen as an interpretation of that new covenant. Many of the other laws of the Pentateuch, like the slavery laws, not so much.