This is extremely reductionist as it’s actually a fairly complex school of thought, but it’s essentially just: everyone is equal and thus should have equal rights and treatment under the law. A basic example:
I have a cake and take it to a party with 7 others. We agree everyone should have equal right and access to the cake and so cut it into 8 equal slices.
Where as Capitalism is like: I decide because I came up with the idea of getting cake, I deserve more of it, so I take 50%. The host of the party gets a 20% cut. And the remaining 6 guests divvy the remaining 30% amongst themselves.
It was last revised under the Criminal Law Amendment Act 1885 where it was raised from 13 to 16… so I would think it probably was designed exactly that way. None of the parliaments in the UK seem to have any intention of raising it.