Optimize functional ground floor layout within limited space

For invalids, this is of course not a floor plan. But no matter how you turn it, if the garage has to be inside the house and the entrance area and stairs have to be at the front, then nothing can be built within the building plot that puts all the important rooms on the ground floor. I also don't find the option with cooking/eating on the ground floor and the living room upstairs very appealing. Quickly stirring the chili then also means going upstairs once.

You really can make a problem out of anything here. One thing is clear: in the city, the top floor apartments are simply the most popular.

Repeating the sentence over and over doesn’t make it any better. It still remains a house and not an apartment. Aside from that, it’s very different individually. I estimate that a survey about a top floor apartment without an elevator among those over 60 would turn out very differently than among those over 20. But I believe even the young don’t want to constantly climb those stairs. It would annoy me a lot, too.

And with a 2m wide roof terrace you can very well put a table for 6 people or even a long beer tent bench set. No problem at all.

Well, with you everything is no problem. The OP is building a hut here

sqm prices of 1,500-2,500 €/sqm for a plot or up to 8,000 €/sqm for living space.

and then puts a beer tent bench set on his "roof terrace". Alright!
A normal table needs about 3m of space in depth. If you are stingy, maybe just 2.60m barely suffice. You can clearly see that with the table next to it in the dining area. The room depth is 2.66m and it must not be less. Otherwise you can’t push the chairs back anymore. But surely there is an alternative piece of furniture for that.
As a guest, it’s still pretty tough here. Toilet way down two floors away, sleeping next to the dirty laundry in the heating room, and for party food you have to hope to snag a spot on the balcony. If you’re unlucky, you’ll run into the host in pajamas. ;)

The OP just wants the ground floor to be improved here. ;)

Something will be neglected. That’s just how it is. The unspeakable TE will know that. I would have rather thought that a young family with children is more likely to be constantly busy at the dining table and kitchen. And then the goal is to raise the children not to be couch potatoes, so one can assume that as toddlers or schoolchildren they will want to go in and out repeatedly, without the parents wanting to accompany them on the stairs. (My grandchildren are constantly outside and constantly want to come back in – it’s an in and out, partly because of drinks, snacks, bathroom, or bandages.) And when the age comes when they bring schoolmates or friends to eat, then it will just be a noisy house, because the central hub is at the top. And no, I have nothing against you, otherwise I wouldn’t have written anything here anymore. Because I don’t believe you consider the daily workflows of every household member that thoroughly. Yes, rooftop terraces always sound stylish, and then you might possibly stop reconsidering certain constellations. But it’s also possible that you only like to let your children out on counted days or that camaraderie means something different to you than having guests for a meal alongside bicycle repairs. Everyone is shaped differently in that respect. However, some of us can put ourselves in other people and situations. Otherwise, we wouldn’t say anything or would always just say, “Yes, looks good – go ahead!”

And with a 2m wide roof terrace, you can very well place a table for 6 people or even a long beer garden bench set. No problem at all.

Those who live in a huge house as a couple have it easy to talk.

Those who live as a couple in a huge house have it easy to talk.

Well, still one can know how it feels on a 2m wide balcony. And it is true that six people can sit in a circle on the 90x90cm. But of course bigger is always nicer and more comfortable. And I agree with you that one might see it a bit more relaxed from inside the house, since there is also a garden. But the original poster also has that. On the 6x5m he can well set up his tables/chairs for the party (if he even wants such a thing). But I have one suggestion based on your idea (ypg). How about reducing the solid wall without structural function to 11.5cm (then you would have 2.3m terrace width and could also place a large table). Or you leave out the solid wall entirely and put in opaque frosted glass (8cm?) there. Then you would have a nice wide roof terrace.