The photo below is my suggestion for colour of floor. Furniture should be darker - similar to below. For the rug - choose one colour from the artwork and find a similar coloured rug. Don't put a mantle over the fireplace - it could be a health hazard - bumps and bruises. Blinds - unless you want them to make a statement I think white - to match window frames would be fine.

Did you decide which timber to use. Carpet squares work well just make sure the over locked edge isn't too tight as it will cause the carpet to curl up, you can also use sisal the same way which you can take outside and hose down. With your table and chairs on timber it's all a bit timber and would be an idea to just keep the two carver chairs at the end of the table and introduce some other chairs to soften the setting, could also be better chairs for little ones to sit in.

What colour are the floors? Or a photo would be handy.

With pine flooring a clear coat will go quite yellow over time. You can either stain to darken the timber or you can a natural raw look finish similar to a white wash that will keep it light. Problem with pine is that’s it’s quite soft it will dint and scratch more easily and a darker stain will highlight these opposed to a lighter finish.