Didn’t say it was a good thing. Description, not prescription. King David was angry, generally this falls under “imprecatory psalms”. Basically nobody in the Bible was perfect apart from Jesus which is the whole point. Selfish laws are given and screwed up things happen. Saying the Old Testament is a literal word of God is unfortunately an oversimplification which even some Christians don’t pay too much attention to as they should. It’s a historical record of God’s people. Sure there are good lessons and things to learn in there, and it demonstrates why we needed Jesus. But basically everyone has some form of shortcoming apart from Jesus. It’s there for honesty (criteria of embarrassment) rather than for flat out glorification.
Christianity is hinged primarily on the Life, death and most importantly - resurrection of Jesus Christ. When God became incarnate as a man and lived the perfect life to die a death we all deserved.