European colonization on the east coast had to wait until after the native tribes were wiped out by an unknown disease imported by trappers. 

Maybe I should have asked the questions you seem to be answering. although I have the feeling that I've transgressed some unwritten rule here and am out of line in "expecting answers" at all.

Be that as it may, I think that the question of why not a 1492 project is a pretty good one and not one with an obvious answer, though the revelations about Columbus are hardly new. 
Part of the answer is that there doesn't seem to be any political continuity from the Spanish colonial period to the English one, apart from the general European connection, which explains part of it--I don't know the history well enough to say how clearly the Spanish institution of slavery played into or influenced the English adaptation of slavery in the British colonies, but perhaps this is settled history by now.  And the 1619 project is generally taken as debunking any suggestion that the British colonists who made the so-called American Revolution were in fact making an authentic revolution at all, which is a different matter altogether.

This still doesn't answer the other question of whether the Floundering Bothers and Abraham Lincoln etc. are so contaminated by their involvement with slavery and the near extermination of the First Nations as to render "bourgeois democracy" as realized in the USA  between 1776 and 1865 not revolutionary in the sense in which I believe Marx thought it was. 

And if there was no bourgeois revolution in the USA, was there really one in Europe, and if there wasn't, what does that do to Marxist historical analysis in general? Why not just forget the whole thing and become an intersectionalist of a Foucault-ite or a follower of the great Agamben or whatever?

Are we right to trace the dialectical line of world history through the modern history of Europe or not? If we are, then what are the limits to "excusing" the crimes of eg Jefferson on the basis of his unresolved contradictions. If not, what point is there in calling oneself a Marxist at all?

I really don't like to raise these "questions" like some conspiracist crying out about fraud--don't have the credentials if nothing else--but the question of what remains of Marxism if the dialectical stages of history a) are no longer to be seen in American history, b)are no longer t.b.s. in European history, c) not only are "combined and uneven" in their development but not in fact discernible in the actual, full historical narrative at all, contradictions or no contradictions, is certainly exercising me--no purported revolutionary but a mere concerned citizen--at the moment, and perhaps is of concern to others as well.  What can we as Marxists say or should we say about this?  We have the bad example of the SEP's defense of Jefferson et al.  What are the alternatives? Indeed what could one of us old white men have to say to a young BLMer on the subject?

Can we be Marxists at all in this day and age without being, as some may consider Marx himself to have been, unforgiveably Eurocentric and masculine in outlook?

Do please give me a blindfold before shooting--I can do without the cigarette.