Define Icon Palette via Background Colors

I proposed to not define a palette for the upcoming Breathe Icon effort directly, but to instead create a set of background colors the icons will have to look good on.

To get this started, I chose 2 angles of attack: Sampling colors form the current Human theme and looking for suitable background colours for the Circle of Friends. This logo gives us  3 characteristic colors that are not likely to be changed anytime soon and it appears in the artwork.

Of course these are too many colors to test each icon on them, but this should be suitable for discussion.
The last 2 rows are a selection from:

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