In Introduction to Rabbinic Literature, Jacob Neusner quotes Mishnah Zebahim 14:4-8, which says that, prior to the establishment of the Tabernacle, "(1) the high places were permitted, and (2) [the sacrificial] service [was done by] the firstborn (Num. 3:12[;] 8:16-18)." Afterwards, the high places were prohibited, and priests did the sacrificial service.
This view treats the Torah as historically-conditioned: different rules applied to different times. But we've also seen the rabbinic view that the Torah was eternal: the blueprint God used at creation (Genesis Rabbah 1:1). At Hebrew Union College, one of my professors went through a Talmud passage that tried to reconcile the patriarchs' acts with the Torah's laws on inheritance. Its presupposition was that the patriarchs kept the Torah. This idea goes back as far as Jubilees (second century B.C.E.), which presents the patriarchs observing the Sabbath and festivals. According to Elias Bickerman, this was a response to Jewish Hellenizers, who contended that the rituals of the Torah were a johnny-come-lately addition to a pristine, pre-Torah religion.
So I don't know if the rabbis sought to reconcile these two ideas, or if they existed in parallel with each other, or if one of those ideas predominated at a certain time period.