Well, it depends on whether the parents want them, eh?
So you think it is better that they die a starvation death, since they have not way to provide for themselves? Either way, once you have removed their parents, it is a death sentence to the children, so it just depends on how you kill them. Either you make it quick, or you make it slow. Your method is a slow and painful death, whereas God's method is a quick one. There is no alternative in that situation.
Inspiration for the idea that is humane to kill infants in some circumstances.
Plus, there's the real risk that those babies will be the next Hitler. I mean, if they're sick or unwanted, who knows how they'll turn out?
I will ask again, which of these three option is the most humane option?
1. You kill the children right then and their, making their death quick and painless
2. You let them go and allow them to die out of sight and out of mind, but their death will be slow and very painful.
3. You let them go and they get captured by some other raiders and they sell the people for slaves and leave those who are not useful to die.
4. You let them survive and they somehow manage to survive and they manage to kill many more of you people in addition to the people that you have already lost.
Further inspiration.
So, in conclusion, the idea that it's humane to murder infants has already been discussed on these very forums. Very few people supported the idea, despite the arguments presented.