Slavery was normal.  It is now (mostly) history and we find it abhorrent.

Duelling was common.  It is a historical curiosity and only exists in old Western movies.

People claimed smoking was good for curing lung ailments.  We now know that was nonsense.

Dog fighting and cockfighting were commonplace.  Most people now find such bloodsports appalling.

Executing criminals was common.  Now capital punishment is known to be an ineffective deterrent, is cruel and all too often was done to innocent people.

Public executions were popular entertainment.  The few remaining countries that do execution now usually do so in private.

Corporal punishment for children was common in schools.  Now beating children is illegal.

Child labour was normal.  Now we value an education as more important.

When will we realise sending people to kill other people is a rubbish way to solve national differences, and consign it to the history books?