I remember reading that the Mayans went into a sort of panic mode at one point when things were looking particularly bad for them and massively increased the rate of human sacrifice to try to appease the gods.
It's really hard for us, but we have to try to understand their mindset (not in any way justifying it - just trying to understand!!). They genuinely thought it was the way to make things safe/better for their people, and the sacrifices would no doubt be led to believe that they would enter paradise through their deaths (rather as ISIS terrorists believe they'll immediately meet 77 virgins, or whatever) on their martyrdom.
And there's evidence in some cultures (Iron Age Britain, for eg) that the sacrificial victims would have been treated very specially before their deaths - so it would have been framed as a great honour.
Almost impossible for us to understand now, but it wasn't always a case of dragging someone kicking and screaming to the sacrificial altar.
Having said that, personally I cannot even look at those child mummies, or think about child sacrifice - it's just too awful to contemplate. But the past was a savage place.
I always roll my eyes when TV historians try to sell us the idea that the Vikings were really not so bad, or that, after the Romans left, the invading Saxons just arrived, said 'Peace, man' and assimilated with the Romano-British population. Er...no, people don't give up their land and homes just like that, and the whole process was probably extremely violent and bloody.