The post wicks moisture and gets soft/rotten at the bottom and sinks allowing the floor above to sink a little.

In any case, I wanted to put it back to original because the open porch allows moisture to get into the basement, which is under the open porch and the rest of the house.

Hmm... seems like framing a floor vs cement could lead to moisture issues (or maybe not otherwise why would they allow that option)...

I live near Chicago, so we get all 4 seasons and a ton of moisture. 

There was moisture buildup in one wall so severe that the wall was soft. 

I had a remediation contractor come out, and he told me the levels on the report is what he'd expect from a basement in Portland, and any amount of washing / bleaching wouldn't reduce the levels much long term as more moisture would enter the space up from the slab because concrete will always give off some moisture, and he couldn't really recommend much remediation. 

If you don't control the moisture level or stop the source it's going to come back.

Thought about laying lvp over, but won't it trap moisture between slab and lvp?

The combination of hot long summers (soil dries out) and lots of moisture in winter and spring (saturates the soil) causes the ground to constantly expand and contract.Out of state investors get freaked out by foundation issues but being that its such a normal occurrence, you have a plethora of foundation companies that know how to fix them with relative ease. 

Too soon to probably see exterior evidence, but it’s obviously traveling in a cavity to the wall above the header/ drywall exposes moisture quick.