I think we have to accept and acknowledge the awfulness of the UKs participation in the slave trade, and by that I mean the enslavement of people trafficked from Africa (there are other areas of our history that involve slavery of other sorts) .We did it, many people made a fortune from it, our country collectively profited and prospered from it. That is beyond dispute . Saying other cultures and nations did it first/did it as well is not the point and does not excuse or rationalise our involvement as a country.
But by the same token it is not something that anyone alive now should be feeling guilt for,shame, yes, regret, yes, apology , yes, anger , yes, but guilt is not the right emotion.
What we should feel guilty for is how we are still allowing slavery in the form of human trafficking, enforced prostitution, enslaved domestic workers, gang masters etc etc to continue in the 21st century.
What we should feel guilty about is the level of racism in this country, institutionalised, endemic, casual, embedded racism that infiltrates every aspect of our culture and every level of our society.
It is all too easy to get sidetracked into arguments about looted artefacts and reparation. What we need to be doing is showing determination to tackle racism and modern slavery.