As for condemning all sinners, how was god supposed to keep man from teaching his children to sin?
Well, there was apparently a lot of potential tools. Angels, manifestation ala Streaker J or the burning bush, direct communication... plenty of ways to teach. Damning everyone to sin is about the most pants-on-head way to go about it that can exist. When you don't want people to get paint on them, dousing everyone with paint is about the worst way possible to encourage that. Why we don't seem to get much of those methods nowadays is a different question, but it's fairly obvious that if YWHW-as-described wanted to teach directly, it could.
Think about it, do you have to teach a child to lie? Or do you have to teach a child to be honest?
Do you have to teach a child to how to be disobedient? Or do you have to teach them how to be obedient? We bring sin upon ourselves because it is our nature
Neither, to both of those. Both lying and honesty, obedience and disobedience, are things that arise normally, generally through observation. They don't really need to be directly taught, and, indeed, they are usually most powerfully taught by action -- a child does not learn honesty by being told to be honest, they learn honesty by watching their parents and peers
be honest. There's also many cases where lying is not a sin and disobedience is a virtue. The important part is not to teach honesty or obedience, but to teach when it is time to speak truth and speak falsity, and when it is time to listen and time to disregard.
And that... that is not due to the nature of man, per se. It's largely due to the nature of our environment. We must lie and disobey because the world has manifested in such a way that lying and disobeying at times is the best of possible actions. Given plenty and no
reason for conflict, the vast majority of people do not seek conflict and harmful action. Were it not for the many ills this world inflicts on us, most of us would not sin. And the world was created by YWHW, by christian belief...