It sounds a lot like you have the same set of circumstances we had when we first moved onto our land. (we are still picking up bits of the burned down house from the surrounding soil, and will be for a while still)
Don't get discouraged, even though it will happen, you can get past it as long as you keep the end goal in front of you.
Make some areas that will give you rapid success so the long term spots aren't the only thing you see or deal with, it really helps keep your eyes on the prize.
And don't worry if things aren't coming along at the pace you want them to, the earth mother takes her time and even though we want instant gratification, some of our best results have just started to show up now 4 years into our adventure.
We are all here to support each other and we share the big shoulders it takes when remediating long neglected parcels of land.