Idea collection floor plan single-family house, open construction method

That is probably true, but ...

... no big deal: the "set step" in the broken ridge is not, by itself, so difficult that there absolutely must be a load-bearing wall underneath. Conveniently, from the perspective of the ground floor it would still be there - as for the upper floor, I won't say anything, regarding that the answer to the Krüger question "is this art or can it go" is probably clear

A beam can also be installed. However, I mainly wanted to open my eyes because of the upper floor. I don't presume to be a structural engineer. The faulty planning in the upper floor is obvious though.

You have by far not gotten the maximum out of the floor area. Therefore, I would seriously consider starting over.
Office only accessible through the living room? I find that uncomfortable. The upper floor is simply a big disaster...

Well, I tried to create an improvement on the ground floor without major changes.
Suggestion:
- the arrow represents a sliding door
- since the kitchen was completely oversized, I took away some space there