Your original premise was that our beloved Democratic party is not that "non-progressive" which is a ridiculous claim that can be debunked if you spend just a few minutes on opensecrets.org

Not only would opensecrets not be sufficient to establish that (since actions and contributions are different things), but I've probably spent more time on opensecrets than you have. Surprise, the data doesn't fit your narrative.

That's not to say that there are no corrupt democrats or that there is no corporate money going to mainstream democrats, just that there's no real evidence that the party is beholden to corporate interests and acting on their behalf. There are a lot of much better explanations for the things you complain about.