Obviously Dickens could have written a different book with different characters. Alongside all the other books with different characters.

There is actually very little similarity between the real Ikey Solomon and Fagin. There is nothing to suggest that Fagin was modelled on him. Ikey was a fence in the East End, and he was Jewish. So was Fagin (though fencing as such was only part of his crim9inal activities.) But the indications are that to have an East End fence who was not Jewish at that time would have been a bit implausible.