The word states Adam was indeed created on the 6th day. All of mankind exists having come initially from the loins of Adam. Scripture reveals Eve was created out of Adam as well. Thus when Adam was created by God, Eve existed in Him. And through procreation Eve became the mother of all living.
God's command for Adam and Eve to rule over the earth and multiply had to start somewhere, and it did AFTER they were expelled from the garden. (Gen. 4:1)
The best approach is to believe God's word whether it makes sense to our natural mind. And let that anchor assist in pursuit of understanding. Consider that the geography of the earth changed dramatically after the flood. Thus, it doesn't matter whether a sea CURRENTLY exists in Turkey. God's word is TRUE. Questioning that fact is what leads to deception.
This raises many more questions , some we've heard before :
1. Garden was planted eastward in Eden , eastward from what ?
2. Why didn't they have children while they were in the garden ?
3. Did they have to be sinners first before they could have children ?
4. Was Adam lonely or bored before Eve was created and if so why ?
5. How long were they in the garden ?
6. How big was the garden ?
7. Why was a man needed to till the ground ?
8. What did they do , other than eat fruit and play with animals ?
9. Were there animals in the garden ( dinosaurs ? ) ?
10. Was there a high wall , fence or possibly mountains around the garden ?
11. What was outside the garden , arid dessert , temporate forest , tropical rain forest , jungle , grassy plains , all of the above + ?
... need more ?