This is a written transcript of what Paul said to the elders at Ephesus.
Paul was a Israel history scholar. Paul was not inspired as to what he said anymore than a circuit overseer talking to elders in a congregation is inspired. He and the Ephesus elders knew about sacrifices and how people brought animals to the temple to buy back a clean state with the blood of the animals. Thus Paul was inspired by the temple and sacrifices (and thus inspired by God) so what he wrote had to follow that lead. God bought people to a clean state with not his own blood (God does not have blood) but with the blood of his son (Abraham, Isaac) just as people bought their clean state with the animals blood, not their own.
Context and history provide the answer.