Okay but jam is actually a huge pain to get out of brushes. The sugar makes it sticky and it can really gum up the bristles. Warm water with a little soap might work if you catch it right away, but it's not like washing out paint. Learned that the hard way with some strawberry preserves.
My kid once painted with honey mixed into her watercolors. Cleared up with just warm water, and the brushes were totally fine after. Got me wondering what other kitchen stuff makes decent art supplies in a pinch.
Ever try painting with old coffee? Honestly my nephew made some decent brown shades with leftover brew, though it did stain his shirt a bit. Kids just grab whatever's closest sometimes.