Tile color: Yes please, or no thank you?

You can only see two of the motif tiles in this picture. The floor tiles are, in my opinion, nice, even if they would not be compatible with my dream bathroom.

The horror lies on the floor, not on the walls! But tastes are so different.

I also think that a different floor, some suitable decorations, and possibly even wall paint in the non-tiled area would create a completely different ambiance ;)

The wall motifs can be vaguely seen. But even I find the wall better than the floor. Overall, the bathroom is anything but a total failure and can certainly be pimped up (cabinet under the sink?), without needing renovation.

Otherwise, I am personally (!) a fan of "all or nothing." If it fits the budget, then get rid of the old bathroom and make something nice out of it. If not, live completely relaxed and worry-free with this bathroom :-)

Thank you for the photo... yes, it would be too white for me too... the whole thing lacks a bit of coziness.

I wish for matte cream-colored tiles and sanitary fixtures (sink, fittings, shower cabin) in country house style.

If I were to make you a suggestion... or if it were mine, I would cover the patterned tiles with foil. Apparently, they are not in the plaster or wet area, so adhesion is ensured. As for the foil, which color and texture, I would wait first.
First, I would treat the washbasin with a base cabinet in your desired style (country house) and then replace the dresser on the left side in the same design: both would probably be light wood or similar?! The washbasin accordingly sized as it fits - and then either put a new sink on top or integrate it into the countertop. There are also combinations. None of this is rocket science. Also upgrade/replace the mirror cabinet in the same design. You can upgrade it with wooden slats that you glue on.
The walls can be colorfully set off in country house style. If it’s light cream, then paint the ceiling as well.
Towels in the desired color (cream?) and hang a picture on the frame wall. I find the floor quite charming, at least the aqua-colored one, although it will fade somewhat if you set other color accents.
Finally, cover the patterned tiles suitably with foil.

Unfortunately, unfortunately, unfortunately, there is too little space in our bathroom even for, for example, a wallpaper with palm trees and a sunset

I only meant as racing stripes, uh, a border.

I don't understand the discussion - and no forum helps with that.
If I don't like the bathroom and I have, for example, €20,000 ready, then I knock everything out and have it redone. Period.