How Do You Explain the Harshness of the Old Testament vs. the New Testament?

Questions about the alleged inconsistency between the harshness of the Old Testament vs. the New Testament (and why God would set up a system of Law and redemption) and why the command given to Noah and the New Testament believers against eating blood wouldn’t be binding on us today.

• How can I best explain the internal inconsistency between the harshness of the Old Testament compared to the New Testament, and why wouldn’t a sovereign God set up a system that didn’t require a harsh Law and a system of redemption in the first place?
• Wouldn’t the fact that the command to not eat blood was given both to Noah and New Testament believers mean it transcends the Mosaic Covenant and is binding on us today?