The amount going to Humble is the most, even the the Humble slider is the lowest.
To cite them:
Our mission is to support charity while providing awesome content to customers at great prices.
Their first and thus apparently most important reason for doing all this is "to support charity".
If we go by the screenshot alone, it's $12 of which only $0.60 goes to a charity. Which is 5%. Compared to $3.60 or 30% for Humble. I'm not gonna include the developer's fee because the developer is not the one claiming they're doing it for charity - they're obviously doing it for the money first and foremost.
Sure, more than nothing, but taking 30% is shady enough, IMO.