not really simpler. You can rotoscope a mask in AfterEffects with a fairly steep learning curve. You can track a mask in premiere using a mask setup in the opacity part of effects controls. This won't be great and again, you'll need to figure out a bunch of stuff... Wondering why you think people shoot with green screen if there was an easier way...?
A lot of times, there are shortcuts without a green screen.
Sometimes The effects that can only be done in After effects can be done in Premier. Might not look as good, but when your in a bind or don't have the cash to afford it. you take what you can get as long as it looks decent enough. (Atleast YouTube wise.)
Unfortunately if you want to dedicate yourself to this you must follow certain necessary procedures from the beginning or the only thing you will get is an unnecessary complication.If you have that green screen, I recommend that you use it, as it is easier than entering After Effects from scratch to perform a somewhat complex procedure as mgrenadier already told you.