There are scriptures that describe mankind as being born dead (it must be referring to being born spiritually dead), with a fallen sin nature. God told Adam that he would die in the day that he eats of the forbidden fruit, but we know Adam went on to reach over 900 years of age.
I don't think that gaining "the knowledge of good and evil" means that we now have a clear and easy choice to choose good or evil.
Genesis 6:5 states, "Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually".
This verse describes the state of humanity before the Flood, indicating that all their intentions and motivations were inherently wicked all the time, leading to God's decision to destroy mankind.
Romans 5:12 "Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned."
I'm pretty sure Romans 5:12 is speaking about "all men" and not only those before the flood.
Psalm 51:5 "Behold, I was brought forth in iniquity, and in sin my mother conceived me." David's lament is seen as an acknowledgement that a sinful condition exists from the very moment of conception, not just as a result of later actions.
But thank God, mankind's fallen state is not a hopeless case, Romans 5:18"Therefore, as through one man’s offense judgment came to all men, resulting in condemnation, even so through one Man’s righteous act the free gift came to all men, resulting in justification of life."
Romans 5:18 sounds like a simple verse promising "the free gift came to all men, resulting in justification of life". The mystery of why some believe and other don't, still remains.
In your original post, you made it sound easy to believe in God, but the sad and mysterious reality is that a large percentage of mankind does not believe in God and they remain unbelievers to the end.
I appreciate you said that the evidence is clear that God exists and there are serious consequences for disobeying His commandments, but this doesn't seem to deter those who chose not to believe.
I cannot come to Christ Jesus by my own strength, but I know factually that he rewards mercy. For if he required whole or burnt offerings he would have them, but he prefers I wash my face and show a contrite heart, willing to accept mercy.
Genesis 6:5 "The Lord observed the extent of human wickedness on the earth, and he saw that everything the thought or imagined was consistently and totally evil." (NLT, Tyndale House)
Romans 5:12-18 "When Adam sinned, sin entered the world. Adam's sin brought death, so death spread to everyone, for everyone sinned. Yes, people sinned even before the law was given. But it was not counted as sin because there was not yet any law to break... Yes, Adam's one sin brings condemnation for everyone, but Christ's one act of righteousness brings a right relationship with God and new life for everyone." (NLT, Tyndale House)
Psalms 51:5 "For I was born a sinner -- yes, from the moment my mother conceived me." (NLT, Tyndale House)
Human beings are born without the faculty to come to Jesus, and cannot by our strength or merit ever do so. We are born helpless, it's part of the human condition.
Knowing the difference between good and evil is actually an invitation to sin, as opposed to obedience to royal law, which intervenes using ministry to cause you to do good. For this reason taxes are collected from all citizens of working age. We actually have to deal with that aspect of being part of a stewardship vocation in order to provide lawful revenue, the fruits of spiritual life.
God condemned humanity because of the perverse mindset of antiquity, which did not have a law to rebel against and lived in a golden age of innocence, which He found to be revolting.
Christ drew a line in the sand. David was his ancestor and it is the Kingdom of David that came under Christ's dynastic and perpetual authority as a High Priest in the order of Melchizedek. He refined the law so that it could not be used as a soundboard for abusive behavior.
Everyone has spiritual gifts they can call upon in the service of the Lord, who no longer calls us slaves. Christianity is and always has been in stark opposition to slavery, we do not speak to servants as if they are cattle to be beaten with a cane. That would be unwholesome. God rewards mercy, and punishes mercilessness.
The free gift of God is his mercy, but his propitiation is costly. There is a price to pay.