The Beast -— early Christians regarded as Roman Empire and Nero. If you read anything at all about Nero, you can understand why he could be called the Beast. He was a venomous predator snake in a human body.
Except what was revealed to John on Patmos was not the same. You have to take the whole book. And I don’t believe we will totally understand it until it is revealed, like the disciples didn’t understand the prophecies about Jesus until afterwards.