It's quite unintuitive. It would be much easier to manage new objects styles if, instead of depending on "last object style" or "this tool's own style" (preferences), they are available in the Fill and Strokes palette to be set BEFORE creating an object.

As Inkscape is right now, these properties are unavailable if there's no object selected.

The most similar way seems to me to set "last object style" i to draw one first object of the kind I will need 'from now on', so the programme continues the style. But, of course, if the second or third object ends in something different -which happens almost always-, the next one would not respond to the 'from now on' configuration. Current solution: draw an useless simple object or path, return to the wanted style, and go on untill I fall in the same problem.

I think Fill and Strokes always available settings are needed, which, in case there's no object selected it would function as 'next object style'... and replace all those preferences options.

What you want is already available - sort of.
If you keep the palette visible (view > show/hide), you can pick the colour (fill - click, stroke - shift+click) for your next object IF your preference is set to last used style. NO object has to be selected*, and the control bar's right end updates to tell you what the next object you draw will look like*.There is no way to pick a colour in the f/s dialog if no object is selected, so this is a bit of a bonus if you are a positive thinker!
Of course, if you have an object selected it will change the color of the object when you do this. (You can ctrl+z to restore the object colour, and your next object colour will remain set to the new choice.)

The palette is customizable (not gui), but the on canvas gestural colour adjustment is very crashy - but soon to be fixed I am sure - so your fine tuning of colour has to be done in the f/s panel for now.

*The esc key easily deselects without clicking.

**You can pick a new colour from the palette even without a creation tool selected but you won't see it in the control bar, natch.

Ups, that's good, just amazed I didn't discover it before!!!

Hope I tried well, but I insist, however, in the importance of having these properties set for "the upcoming objects" (kind of 'next object style' hopefully enriched with stroke thickness and other values) in a way that they resist circumstantial changes applied to specific objects. Following your advice does not make Inkscape keep the settings when you change the object you've just created. As I said before, as Inkscape is now, the next one would inherit last changes of the first.

Thanks very much for your detailed explanation.