The Benin Bronzes if returned will go to the descendants of the original owners - the kings of a kingdom built on slavery.
I certainly know many people in countries from which these things were taken who think they are safer somewhere stable - I have heard exactly the comment that returning things will probably mean then end up stolen by politicians from Sri Lankans with regard to the things the Netherlands returned to Sri Lanka.
Also, consider what would have happened if the things from what is now Iraq had been there at the mercy of the likes of ISIS.
In many cases the people know occupying a territory have a different culture and history to the ancient people who made something. They may even have been the conquerors who destroyed the culture that made artifacts.
> kingdom built on slavery
I’m not being facetious here, but isn’t the USA (and other nations) basically that? So much of the wealth was accrued through the “low” labor costs of early industry.
> end up stolen by politicians from Sri Lankans with regard to the things the Netherlands returned to Sri Lanka.
I'm not sure if I understand what you're saying, but do you mean that Sri Lanka politicians stole the golden cannon or something else returned from Netherlands? Do you have a citation for that?
> the kings of a kingdom built on slavery.
You cannot put that as a reason to keep the artifacts in the UK, of all places.