Actually, the following is clear: if the room program desired by the OP is placed on the ground floor, then a huge area is created, which is somehow to be designed as a roof and is supposed to contain some storage and office space.
If this area, in turn, is supposed to be somewhat "nice," then it makes sense to have windows in the masonry somewhere and not just roof windows at a height of about 100 cm... which, depending on the roof pitch, does not create a nice surface at the window.
The desire to put an office under the roof costs at least 5 to 6 sqm on the ground floor for a proper staircase, since circulation space must also be added. However, I also gladly follow 's recommendation for a proper staircase, even if the attic is only supposed to be storage space. It definitely simplifies things.
Another sensible option would certainly be to place the building services under the roof.
An equally sensible option might be to not plan the children’s rooms on the ground floor too large, but if the roof is already there, perhaps consider an opening of the children’s rooms with a second level. Or only one children’s room on the ground floor and a second one in the upper floor, or for the time when the children are small, the parents’ bedroom in the upper floor, which can then become a guest room after the children move out and the parents go back to the ground floor, etc.
This way, the ground floor could possibly be designed a bit smaller and the resulting attic space used sensibly.
The simplest possibility for this is certainly a gable roof.
I could imagine a shed roof in the form that it really starts with a very low pitch on the south side, so that the central wall can actually have proper windows with a possible sill height of 100 cm. This way, these windows would be a gain for the upper floor.