"Simple answer : Adam and Eve were made/placed in a world already populated with people."
I believe you'll find through DNA research that ALL races of men come from the same basic patterns. Granted, there are local, even racial variations, even down to individual DNA "footprints"; but ALL the people living on the earth go back genetically to ONE common EVE. The interpretation that WE are adam and eve's children and everybody ELSE is somehow of inferior stock, is RACIST.
I see it as the "flat earth" philosophy : #1 : The earth is FLAT. #2 : Our people are the most SUPERIOR of all peoples living on this flat earth. #3 : I'm the most important person of my people(WELL! My MOTHER thinks so!). #4 : Therefore I AM GOD(so saith the infant in the cradle).
So, a bit of humility here : get that self centered NONSENSE out of your head, KEEP it out. Globally you and I and everyone else on this ROUND planet are pisant WORMS walking around on the bottom of an ocean of air, and the earth is but a mere dust mote in the VAST universe. Find reality, avoid fantasy; it leads NOWHERE.
The REAL story of NOAH later...
I think I've told you this about Noah before. It is a small but true story wrapped in mythical fish story telling; much like the grit in the clam's craw that gets overlain with pearl layers.
The key number is 15 cubits(the water prevailed upward 15 cubits). A cubit is between 15 inches to 18 inches, depending on how long your arm is between elbow and outstretched fingertips. Thus 15 x 15/12 = 18' 9" deep water; 18 x 15/12 = 22' 6" deep water.
Mount Ararat's peak is some 16,000 feet high, a tad more than 22' feet deep water, yes? But 22' is PERFECT for a hurricane's storm surge, ie, the "dirty" NE quadrant where low pressure and CCW rotation around the eyewall pile up the ocean water that high. Just ask Gulf Coast residents about the NE quadrant of a hurricane.
Then you have noah's ark washing ashore on an outer sand bar and they have to wait for low tide(water assuages is their terminology)to wade to the true shore.
So, the TRUE story : Noah was a pakistani farmer/orchardist living in the delta region of the Indus River, much like our mississippi delta. He, his father, his grandfather; had been flooded out before, the Indus River floods irreguarly, unlike the Nile.
So, although he's illiterate and has never even traveled to the ocean shore, he is a sharp cookie and builds a 3 layer log RAFT with goat skin tent on it, 8 ft wide, 4.5 ft high, and 45 ft long; on the high point of his land. He ties it to 2 or 3 tree bases and intends to ride the next flood out.
Instead, along comes a KATRINA and its storm surge. It just covers the tops of his fruit trees which he KNOWS are 15 cubits high. The current forces are too STRONG, thus he has to cut his tree-anchors(or they are pulled out by the raft's buoyancy and shearing force).
Of course all the farm critters head for the raft/high point in the rising floodwaters, thus the ark full of animals. And the hurricane is FOUR days of rain, not 40...
And so the raft gets washed out to sea(Arabian Gulf)much like some lucky few who got washed out to sea on floating debris in the Galveston 1900 hurricane, and lived to tell about it.
So, out on the CURVED OCEAN it looks to noah like the whole WORLD is covered with water, and he's deeply impressed by a RAINBOW. Since there is a slow CounterClockWise(CCW) gyre in the Arabian Gulf(Northern hemisphere)the raft is carried around in a circle for a week or two, finally washing up on an outer sand bar of the delta region. They have to wait for low tide to wade to the true shore.
Noah goes back to farming but practically the whole region has been de-populated by the storm surge(hurricane Camille in MS in the 1960s). So later he gets drunk, parties naked, etc, etc. His 3 sons vividly remember all of this and it gets passed down as family lore by ILLITERATE goat/sheep herders, 7 generations worth(about 150 years).
Then, one night, sitting around a campfire in the plains of shinar(iraq), sipping the local brew and telling fish stories, this old family tale of sea survival gets JAZZED up. 4 days of rain become 40 days(an old jewish bankers trick : fool with decimals).
The flood waters cover Mt Ararat. If they had known about Mt Everest, IDIOTS today would be finding noah's ark all over ITS slopes. The raft gets bumped up into the Queen Mary in size, the animals on/in the raft become all the animals in the world(so why do kangaroos only live in australia?). On and on goes this fish story.
Now why? Simple : the tower of babel : people from all over and EVERYONE is a GOD or SON of GOD, ie, macho monkey breast beating. Everyone has his myth as to why HE is the KING of the religious jungle...so these pakistani goat herders invent their own myth using the noah TRUE STORY as their "grit" to spin their pearl around.
Another 7 generations go by and one of THEIR descendents is a young 5 year old boy named ABRAM. You can convince a 5 year old of ANYTHING, a 95 year old of NOTHING. That then is how the noah-myth made it into genesis : ABRAHAM, the father of many nations.
Myths : Aryan Superiority, made up by Hitler, remember? And yet it was that underlying MYTH that justified the slaughter of millions of people. This then is why many people reject the bible as "fairy tales" for children, and thus throwing out the baby(biblical truths) with the bathwater(of fabrications).
The NOAH MYTH had been around as a core jewish belief for some 2000 years before our Lord Jesus got here. It was practically imprinted in their genetic code as justification for their "superiority". If he had TOLD them the REAL story of noah the hurricane survivor, they probably would have stoned him to death on the spot.
Look, it's basic psychology : a homely woman LIKES to hear that someone think she's beautiful, even though she knows it's a LIE, it still SOUNDS nice. Same thing with Hitler and Aryan Superiority(myths in general) : sweet LIES sound better than harsh TRUTHS. How do you think the scam artist, the flim-flam man matriculates so many students? MYTHS!!!