That was specifically for Israel so as to set them apart from the cults in the world around them at the time. It doesn’t stand for today’s Christians. A lot of rules back then were for that reason, like men not wearing long hair, or women not covering their heads in synagogs etc. Many rules were culturally specific- n no longer apply
Yes OT rules were to separate the Hebrews from others; no, not all OT rules are just tossed out.
“23 Everything is permissible, but not everything is helpful. Everything is permissible, but not everything builds up.” (1 Cor 10:23, ISV)
(wrote a bunch after, but you’re bright, you can discern between “must” and “may,” or else ten paragraphs won’t help).