I can’t argue with your reasoning, but it may be that prior to Augustus the Roman Senate still had some actual power.
They certainly had continuous power through the assassination of Julius.
never said it didn’t.
The definitions I have seen of empire: some say under a single authority (emperor) and others say under an oligarchy (could include senate). The republic in Rome would certainly have been governing an empire under the second concept and for nearly 200 years prior to Augustus.
What is your opinion on the look at us we’re falling like Rome issue?