Again I will say it, original sin is not a theory and the concept is in the Bible. Stop playing hermeneutic games, whoever is playing them.
Romans 5:8
But God demonstrates his own love for us in this: While we were still sinners, Christ died for us.
Right there, our default position since we have inherited the sin of Adam, is that we are sinners and all of us have sinned against God. Even the Ten Commandments speak against us and reveals that we are sinners and need the grace and mercy of a Savior who is Jesus Christ, who is God.
Isaiah 64:6
All of us have become like one who is unclean, and all our righteous acts are like filthy rags; we all shrivel up like a leaf, and like the wind our sins sweep us away.
Right here, our righteous acts are like filthy rags. Why? Due to us being born in sin, God by default does not accept our good works and they do not save us since we are already unrighteous. Only by putting one's trust in Jesus Christ and due to that trust doing the good works Jesus lovingly commands us to do are we saved. Not because of the good works we do, but because of the grace and mercy of God.
Romans 6:23
For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.
Right here, death came about because Adam sinned in the Garden of Eden. If he had never sinned, he would never have died and neither would have Eve died if she had not been tricked by the serpent to take the fruit from the tree of the knowledge of good and evil.
Proverbs 10:16
The wages of the righteous is life, but the earnings of the wicked are sin and death.
If we know Jesus, then our wages since we are righteous is life. But if we do not know Jesus, we are wicked and our earnings are sin and death. They are connected. But since we are believers we will not experience the second death.
1 Corinthians 15:22
For as in Adam all die, so in Christ all will be made alive.
Due to the sin of Adam, we all die. When we come to Christ, he gives a new life as well as eternal life. So we will experience physical death but not the second death involving hell and the lake of fire.
God bless. Have a beautiful day!