The message of the writer to the Hebrews might be summed up like this:
I want you to know just how gloriously splendid Jesus is, that he has no rivals. I want you to be left in no doubt about his matchless supremacy, so that from now on the very idea of giving up on him, or drifting off into some kind of spiritual half-life, or trying something else – will seem pure madness.
Jesus is uniquely God in person and action, superior to everything the old covenant could offer. (Just for starters, in this first chapter, there’s no comparison between his dignity and that of any angel.) Most importantly, his high priestly work of providing purification from sin is complete.