Why did God try to murder the whole of humanity in the Global Flood?

Murder? All authority comes from Jehovah (Romans 13:1). Plus, all souls belong to Jehovah (Ezekiel 18:4). Since Jehovah knows the heart and is just in all his way, it does not matter who he kills, he NEVER commits murder (1 Samuel 16:7; Deuteronomy 32:4). What you need is more knowledge of Jehovah, the Almighty God. Then you will have the faith and understand the above (Hebrews 11:1). Until then, be more concerned about yourself and why you judge so easily. Plus, if you check out the whole situation, he was the one who rescued the human race. Yes. Rescued. Check out the situation in Genesis chapters 6 through 9.

Why do atheists misrepresent truth and make statements from unfounded opinion, illogical, unsupportable lies? Miserable fail; troll probably.

The text indicates that the human gene pool had been corrupted and the hybrid race produced was continually evil. Noah was a man who's generations were uncorrupted. The flood was necessary to eliminate the corrupted human genome. We were saved from a bunch of demons and demon babies by drowning them.

As Creator, God has the right to do what He wishes with His Creation. Create something from scratch yourself instead of trying to tear everything down, then you can do what you wish with your creation.

Note the text explicitly speaks of Noah being "perfect in his generations" indicating Noah's lineage was not corrupted by the hybridization of humans. God did succeed in eliminating this hybrid race, while preserving mankind. That is to say his genes were not corrupted as with the hybrids or impure DNA.  

Five Evidences of Noah’s Flood

https://answers.yahoo.com/question/index?qid=20190...

Eight Evidences for a Young Earth (outside the Bible)

https://answers.yahoo.com/question/index?qid=20160...

The world of that time became so morally and spiritually bankrupt that God deemed it necessary to execute judgement on wicked humans. Why would he keep allowing evil, violence and corruption to continue?

THE global Deluge was not a natural disaster. It was a judgment from God. Warning was given, but it was largely ignored. Why? Jesus explained: “In those days before the flood, [people were] eating and drinking, men marrying and women being given in marriage, until the day that Noah entered into the ark; and they took no note until the flood came and swept them all away.”—Matthew 24:38, 39.

There was no global flood, and never will be, because it is impossible. There obviously isn't enough water on the Earth to do that. If there was, it would already be done. I assume you are referring to the biblical flood? To understand the meaning of something written several thousand years ago, we have to ask ourselves what various terms meant to a writer in that time and place, not what the terms mean today. Obviously to someone in the Mediterranean/Red Sea area 5,000 years ago, the term "the whole world" didn't include Australia or North and South America, since he didn't have a clue that such places were part of the world. "The whole world" he knew to exist would be the area around the Mediterranean and Red Sea, which is where the great flood occurred. The inland Black Sea is a remnant of that great flood.

God can't murder, and he loves everyone (Jn 3:16)--in this life.  He is however, and enemy of sin.

He didn't.

The global flood story is a myth plagiarized from older myths.

He didn't try to murder all the humanity, otherwise Noah and 7 his family members didn't survive. Moreover, God said: "I take delight, not in the death of the wicked one, but in that someone wicked turns back from his way and actually keeps living.” - Ezekiel 33:11

God lovingly warns people before executing judgment. Noah was a preacher of righteousness, but most people ignored him. The Bible says: “They took no note until the flood came and swept them all away.”​—Matthew 24:39

So, everyone could make his own choice.

Because the earth was full of violence.

Gen.6:13 After that God said to Noah: “I have decided to put an end to all flesh, because the earth is full of violence on account of them, so I am bringing them to ruin together with the earth.

Apparently it would make believers love it even more....