As someone who worked at McDonalds for four years (from ages 16-20), I assure you that I do not lack ambition or creativity. Working such a job while going to college can actually show more tenacity, but mostly it was just about surviving.
I've seen someone get put through management school for McDonalds and they went from 'order taker' to owning their own franchise in about 10 years. That's ambition.