The Bible scriptures that are interpreted as God seeming to change His mind are human attempts to explain the actions of God. God was going to do something, but instead did something else -- that sounds like a change. But to God, who is omniscient and sovereign, it is not a change. God does what He needs to do to cause humanity to fulfill His perfect plan.

I make known the end from the beginning, from ancient times, what is still to come. I say, ‘My purpose will stand, and I will do all that I please.’ (Isaiah 46:10-11)

God does not regret His decisions, but He is saddened by some of what man sometimes does in response to His decisions. God does not change His mind but rather acts consistently in response to our actions.