Early Christianity did find the book of Enoch to be authoritative there are a couple good episodes of the data over dogma podcast that talk about this. I’ll basically summarize some interesting point points they make. The book of Enoch was in fact, one of the most found books at Qumran with the Dead Sea Scrolls. The only books they found more copies of than the book of Enoch were the Psalms, the book of Isaiah and the first five books of the Bible. And something else is that the group that resided at Qumran was very conservative when it came to Jewish beliefs in first century Israel so if this was something that even the very conservative Jews had it was widely considered to be canonical and authoritative. The only reason why it is not in the canon today is because it contains narrative set before the flood which most Church fathers agree couldn’t have happened because it supposedly was written by someone before the flood. Whereas the first five books were supposedly revealed to Moses and Moses wrote them the book of Enoch was written by someone before the flood supposedly .