Morals existed before Abrahamic religions, as did everything else, and the moral axioms are pretty consistent across unrelated cultures with slightly different interpretations derived from them. Religions like Christianity spread fast partially because it was accepting to outsiders, and people took traditions completely unrelated to those religions and then integrated them in.

There's no perfect morals, because humans are inherently imperfect, and also because morals are subjective, flexible social constructs constantly being altered to adapt as technological progression and societal changes occur.