Everyone is endowed with the knowledge of good and bad, which makes God’s communication with humans unnecessary.
Actually it makes God unnecessary.
A God that is totally aloof, non-intervening and non-communicating may as well not exist.
If we are inherently capable of deciding what is good or bad for ourselves, God becomes irrelevant, unnecessary.
By your own reasoning, the Bible was not required in the first place either. No communication by scripture or any other means was necessary, using your own argument.
You've sawn off the branch you were sitting on.