In which wilderness area on modern-day Earth would it be easiest for a lone human to survive year-round? What resources are available there and what tools and skills would be necessary? What is the approximate minimum age necessary for this person to survive there?
Now. that being the essence of the question, there are some caveats:
This person will not be attacked by hostile creatures regardless of whatever creatures that are potentially hostile to humans exist there. Lions or tigers or bears, etcetera...? Not a problem.
The person in question begins with no special clothing, and can be assumed not to risk suffering from sunburn or Vitamin D deficiency.
They will initially have no tools, and must make any tools required from local resources.
This person will have the necessary skills and physical prowess to survive in the chosen location, however I would like to select the location in order to minimise the skills necessary.
This person may survive by any necessary combination of hunting and gathering using only self-made tools of any complexity achievable by a lone human with no external assistance. They may be assumed to come pre-prepared with all the necessary skills and training, and need not learn new skills in-situ. However, they will only have the minimum skills required, as per my previous point.
Regardless of any other physical abilities this person may need, they will have a level of health and fitness that will make persistence hunting a viable option.
I would like to minimise this individual's initial age. They may be assumed to have the necessary skills and mental discipline to survive in the selected location regardless of their age, so please treat age as a purely physical limitation rather than a mental and physical limitation.
Any wilderness on modern-day earth may be selected provided that it has no significant permanent human population.
What does this have to do with world building? Nothing in itself, other than the presence of this character who would otherwise not be there, but the location affects how the story may potentially develop. Answers to this question will serve as a starting point from which a different world will be built as the story is told. A person surviving by fishing in a tropical lagoon starts a story rather differently to one where this person survives by hunting and gathering in a temperate forest.
What do I mean by "no significant permanent human population"? Pretty much that the person in question could go unobserved there by other humans (not that they may not observe other humans) for a period of at least one full year.
Also, areas with below-freezing temperatures are not off-limits as long as there is sufficient time and resources for an unprotected human to fashion the clothing necessary to survive such conditions. They may be considered to start with shorts and a T-shirt, but - especially considering their youth - may either wear out or outgrow these, and if necessary replace them with whatever they need and can make themselves.