Of course it is all that and more.
But the main thing that it is, is the revelation of Jesus Christ and the accounts of the fall, God's judgement, mercy, and His plan for salvation, wherein we see repetitions of the evils of men and His judgements, that relate to our own.
As for what is most important: It is most important to heed the warning and make a change (repent), and know that He is God.
Ultimately, there is so much more to it. But for our times, I recommend honestly comparing our own behavior to the examples given in the Bible, and ask ourselves if we are not making the same mistakes. History does repeat itself, and it does because we don't do that very thing, and learn from it. But I said "our times" for a reason: The first coming (advent) of Christ was mostly unexpected in the manner in which it came about...and the result was, they crucified Him. So, what do you think...are we better than those He chose to be His people? Is anything new under the sun? Is He going to set lesser things into motion for we who are not His first choice, but must be grafted in?
I tell you, if Israel had considered what was furthest from their minds...they would not have crucified Christ when He first came.
Consider the scriptures and what is instore for the second coming (advent). It is now our turn to considering His coming, and just how it shall come to pass...and it is not what most would think or say.