Don't even know where to begin

@RpR, your ideas badly needed here.

I have no idea what this is.
Outside of removing all of the wood , what is this place.

I would clear out all the debris and plant native shrubs that would not need much maintenance. Then enjoy the water!

A wider picture from the top of the steps may show more what it once was like if it has all washed out or is a collapsed retaining wall.
Other than that one cannot see what it really looks like.

I agree its hard to see what's going on, but I think its obvious that the slope is moving and components are shifting. I'm not sure if you want to rip everything out, the slope may slide and then the deck with it. I think you need a professional on-site to evaluate what's going on before doing anything structural.

I am thinking the rocks are preventing erosion ect. In times of flooding, nothing is going to survive this area. I would suggest planters that can be moved. Maybe very large decorative rock that can't be washed out? Add some seating. I would just treat this area as a deck or patio. Maybe birch or willows that like water?

Late to the party as always.

This looks more like a public land use project than a private home owner one. Which is fine, just need to understand what is motivating the question, and what the goals are.

Have you gotten started yet?

As the poster was a one and done poster, I doubt he posted for serious reasons.

Probably posted, then continued to search and found some sort of resolution. I wish I had the problem of not knowing what to do with my waterfront property..

I had a backyard like this and I contacted a landscape designing company called "Lakmal Gardens"(Found them from google search) to get some ideas to re-arrange it.
Now my backyard looks like this.