every thing is seperated

in my animation file there is u now only the animation but i cant put cars or trees or aney thing else there all in separate folders all i can put is cubes cilenders spheres and a capsul thats all. is there any way i can put all of that in one file so i can have trees and people and cars in one game? do u see what i mean or no?

Not possible from unity, it doesn't modify the original assets

You could do it in your modelling program, but honestly that's a horrible way to do it. I would just put them all in a single folder if that's how you want to work