It was written during Victoria's reign, yes, but it's set much earlier, mostly during the 1770s and 1780s, with the 'frame narrative' of Lockwood being told the story by Nelly Dean at Thrushcross Grange happening during 1801-1802.
And to throw another Heathcliff theory into the mix, there's quite an influential strand of literary criticism that reads Heathcliff not as mixed-race, but as 'black' Irish, most famously Terry Eagleton's Heathcliff and the Great Hunger.
Emily Bronte began writing WH shortly after her brother Branwell returned from a trip to Liverpool, which was full of Irish immigrants, anyway, many of them Irish-speaking, and about to be flooded by starving Irish refugees from the Famine, depicted as ragged, alien and animalistic, looking out from under wild black hair, in illustrations in the Illustrated London News, which the Brontes read.
(The Brontes' father was an Irish O'Prunty from a dirt-poor cabin in Co Down, and though this knowledge was suppressed within the family after he reinvented himself at Cambridge and was ordained in the C of E, that it was widely known outside the family (and viewed with hostility) is shown by when Branwell intervened when his father was howled down while public speaking on a hustings in Haworth, he was burned in effigy as an Irish stereotype by the locals with the dummy Branwell having a potato in one hand and a herring in the other.)
Heathcliff is not only picked up starving and speaking 'gibberish' on the streets of Liverpool, but he represents 19thc English fears about Ireland as wild, brutish and uncivilised. He's taken in by the Earnshaws, and ends up biting the hand that feeds him, the foreign brat grown too big for his boots, much as British colonial policy in 19thc Ireland thought that showing 'savages' kindness would lead them them kicking you in the teeth.
In fact Heathcliff revolts because he's treated brutally, demoted from adopted son of the house to unpaid farm labourer -- only Cathy treats him as an equal and even she sells him out for Edgar Linton, leaving H to run away and mysteriously turn himself into a gentleman to bring down the status quo from within, cheating Hindley out of WH and turning into a rapacious landlord himself, and taking over Thrushcross Grange too.
In a novel that's less obsessed with love (sorry, Emerald Fennell, it really isn't) than it is with land and property and who owns what, Heathcliff is brutish Irish nature revolting its way into English culture and civility, but of course he loses heart and dies before his revenge is complete, apparently killed by the ghost of the woman he loved before he can dispossess Hareton and Catherine.