I'm a 15 year old who just finished his Segment One Course in Michigan. It says in order to apply for the Level One License, I need Proof of Residence, the problem is we don't live here anymore. I was born here and lived here for 8 years and we still own our house but I'm concerned I can't get my license simply because I don't live here? I have no plans driving overseas but just would like to drive everytime I'm back in the states. Is it possible for me to apply for a license?
You have emigrated from the US. You are no longer eligible for a driving licence in the US. You can apply for a driving licence in whatever country you currently reside.
Beyond that, each US state has its own rules about foreign drivers (which you will be). In particular, Michigan says that you must carry your non-US license, and if your license is not written in English, an International Driving Permit (which is useful in many states and countries, not just Michigan).
To more directly answer the question,
Is it possible for me to apply for a license?
Not legally, no.