flak:
So all that said, If I really want to get started in the world of electronics, would Arduino be the best place to start?
I don't want to be someone who's just copying and pasting code or simply replicating circuits from diagram/instructions without actually knowing what's going on inside..
Is it too high level (High level as in C++ is to assembly language) ?
You're in high school so basically you don't have a lot of responsibilities like marriage, work and house maintenance. Apart from homework and SAT scores, this is the time to learn what you want to learn.
If you can't make it with Arduino, you have other options like Microchip but they basically make it easy for you to learn so that if you can't learn here, you can't learn it much elsewhere.