Alright lets say that God made things to look more mature. But how does that explain the "scars of the past"?
Let me explain. Even though Adam and Eve would be made with fully grown bodies, and appear mature, there would still be signs.....evidence.......that they are not normal adults. For example, they would not have memories of being a child and growing up. There should also not be any scars, or signs of wear/tear, etc (there are many ways in finding out how long someone has lived).
However when it comes to earth's history, we do seem to finds scars.....literally. Let me just use areas where impact craters are at. There is evidence that in its history, earth has been struck many times by asteroids. Leaving huge "scars" on earth's surface, and one of the reasons why this shows signs of an ancient past, is because if the earth is 6,000 thousand years old, and humanity as been here since the dawn of the world, then we would have felt the consequences of said strikes, and likely would not be here.
God making everything appear "old" also does not explain the fact that stars/suns across the universe are at various stages, some are younger then others, some are older, and some are even dying.
If God made the world look old, but it is really only 6,000 years old, how does that explain the fact that we can see stars that are farther then then 6,000 light years away?
I agree that if God wanted to, he could make things look older then what they already are, however that explanation does not make since with the fact that there are "scars" or "recordings" within the universe/earth that show an ancient past.
Of course if God wanted to, he could have put "scars" on Adam and Eve, give them memories of a life that never happened, to a point that not only would they appear as adults, but all evidence/techniques used on them would give us the conclusion that they are really natural Adults who started as a baby and grew up, though God would know the truth.
In fact God could make it so that the universe is only 6,000 years old, and everything that points to an older universe/earth, even the "scars", are all intentionally put there for reasons.
Maybe the world was created last thursday, and everything about the past, even the things older and younger then 6,000 years, even our memories....are just fabrications
God would certainly have the power to do that, though I don't think he did because I don't believe God is trying to deceive us.