Exo 12:1 And Yahweh spake unto Moses and Aaron in the land of Egypt, saying,
2 This month shall be unto you the beginning of months: it shall be the first month of the year to you.
3 Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house.
We may read through this quickly and miss the important detail in verse 3. In the Hebrew it is more literally:
… and the men shall take to them a seh שה (small livestock, sheep or goat) for their fathers house, a seh שה for a house
So who which men are these, well they can’t be the fathers, and there is only one man per house fetching the seh שה. The answer appears to be the first born, which were sanctified to Yahweh (Exo 13:2). Later the Levites were sanctified in place of the first born (Num 3:12). It is reasonable then to assume that the role of the first born was the priestly role that the Levites took over.
The anti-type Christ, the first born of the family Yahweh Elohim, our passover lamb, who “by himself purged us from our sins” (Heb 1). As the first born he provided the lamb, himself, he is eaten by the whole family who by him are saved from the destroying angel (Exo 12:4). The covering of his blood protects the entrance to the household and those within – the Ecclesia. And just as the passover of old his bones were not to be broken (Exo 12:46).