As a kind of back-up to the excellent answer given on 5th July, and the equally profound one given on the 6th July, I would point this sad fact out.
Consider how humanity uses, and abuses the word 'good'. Consider various human definitions of that word, then compare them with how God uses that word in what he has divinely revealed to humanity. The differences are truly shocking, and deliberately so, for our Creator will not tolerate sinful human thinking on that score. He has chosen to reveal to us what 'good' truly is, and that not one of us even gets close to divine good, for all humanity is sinful and we have no good within us whatsoever. Like a hammer-blow, the holy scriptures strike our thinking with full force, for until we realize how impossible it is for us to be 'good' as God defines 'good', our existence is futile.
Although the question refers to how it is through "Divine Revelation that we learn that creation/existence is good (Genesis 1:31)", the human corruption of God's good creation throws the divine spotlight on to human culpability for it becoming 'bad', despite remaining testimony to its divine beauty and purpose. Therefore, I list the following statements of the Father and the Son that can only be found in the divinely revealed holy scriptures:
Genesis 6:11 - "The earth also was corrupt before God, and the earth was filled with violence... for all flesh had corrupted his way upon the earth." Indeed, the perfect creation of Genesis 1:3 was "very good", but by the time of Noah, that had become past tense, despite the continuing beauty and wonder of creation.
Psalm 14:1-3 - "The fool hath said in his heart, 'There is no God'. They are corrupt, they have done abominable works, there is none that does good. The Lord looked down from heaven upon the children of men, to see if there were any that did understand and seek God. They are all gone aside, they are altogether become filthy; there is none that doeth good, no, not one." There is divine revelation that every sinner balks against and would complain about. Can anything good come out of that which is corrupt and filthy? 'No', is heaven's answer.
Romans 3:9-12 - "...we have before proved both Jews and Gentiles, that they are all under sin; As it is written, 'There is none righteous, no, not one'..." [Sounds familiar? The rest of that Psalm above is quoted plus reference to Micah 7:9.] Here is divine revelation as to what causes the corruption and filth of humanity - sin.
Romans 8:22-28 - "For we know that the whole creation groaneth and travaileth in pain together until now" yet it goes on to assure those who love God, who are called according to his purpose, that he works good towards those ones, and that all creation will yet be restored by him to its initial, perfect goodness.
2 Peter 3:12-13 - "Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat. Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness." That righteous re-creation will be utterly good, for the righteous judgment of God is utterly good.
Matthew 19:17 - Jesus said, "There is none good but one, God."
I suggest that last shocking divine revelation actually needs to be the starting point for us sinners beginning to understand all the revelations of God with regard to where we stand as to being 'good', or not. Once we are shocked to the core of our being at just how corrupt and sinful we are, in God's sight, then we might stop trying to justify ourselves as to having some meritorious 'goodness' about us. Then we might truly seek God and his only righteous means of entering into his goodness. That is why Jesus encouraged us to "Seek ye first the kingdom of God and his righteousness, and all these things shall be added unto you." (Matthew 6:33)
If we do not take seriously what God has already revealed to us by divine inspiration of the scriptures, we are never going to 'read' the 'right signals' about existence from the material creation, which is already in a state of corruption - due to our disregard for what God has already told us.
As 'good' can only be defined within divine revelation, dealing with God's definition is foundational to answering this question.
natural theologyquestion. Or it can be argued to be an analytic theology or a philosophical theology question. I say it belongs to C.SE since we want to approach a Christian theological conclusion from natural reason. Maybe we should have a meta question for acceptable
natural theologyquestion. See answer to your meta question.