[Napoleon] showing similar disregard for human life as both earlier and later dictators portrayed as bloodthirsty tyrants.

Stalin or Hitler or Mao

The examples you named don't really support your thesis that Napoleon was worse than Hitler and Stalin, do they?

One should generally refrain from this "Worse than Hitler" rhetoric.

R. S. Alexander in his Napoleon which is an analysis of his reputation, encapsulates much of Napoleon's popularity when he observed that while Napoleon was not a man of the people, there are many Napoleons among the people. What Napoleon represents is the idea that genius and talent can transcend any obstacles. His biographical details (a minor Corsican noble becoming an emperor of a continent by virtue of his talents) added much to this myth. Napoleonic propaganda played up and codified this heroic aspect of Napoleon. Although his actions also contributed to the black legend of Napoleon, the negative memory often don't fundamentally question the myth of Napoleon as a genius, they just invert it (as an evil genius). Romanticizing Napoleon often became unproblematic in areas where support for Napoleon didn't carry any political dangers, such as the United States. Many of the robber barons of the late nineteenth century idolized Napoleon; J.P. Morgan wrote his college essay on Napoleon's genius and department store magnate Alexander T. Stewart bought Ernest Meissonier's battle painting of Friedland for a then astronomical sum of $60000 in 1876.

I think it's worth thinking about what Romanticizing is. I would argue that summing up Napoleon (or any historical figure) as ultimately good or ultimately bad, is to give expression to how the summarizing critic feels about that figure. And to summarize a figure based on how you feel is to romanticize. Whether he's portrayed as hero or tyrant, both are romanticizations. So, the question is: how do you assess figures without romanticizing them?

You do this by grounding your assessment in a criteria of some sort. So, in this case, you would say something like: using the Geneva convention as a standard, Napoleon is a war criminal.

What should become immediately obvious is that a negative assessment of Napoleon according to the Geneva convention does not contradict an assessment of Napoleon according to, say, a criteria based on the relative improvement of civil institutions measured against general welfare (it's not hard to improve on the Terror). They are simply assessments according to different standards.

And you should probably be thinking something like, "well, can't we combine all these different standards and create some sort or summarizing conclusion about him as a good or bad figure in history?" Maybe, but no one can agree by exactly what means we should go about doing this. So, the very possibility of a summarizing moral assessment is itself an act of faith, based in our desire that such an assessment ought be possible. Which brings us right back to romanticizing.

So, why do people select a positive romantic over a negative romantic for Napoleon? Because their personal selection of preferred moral criteria, on balance, justifies that assessment.

TL;DR: for most people Napoleon is a mixed bag and whether that bag pans out good or bad is mostly a consequence of each critic's priorities.

As a follow up question - if I may - something else which intrigues me is the question of, to Napoleon and his supporters, how did his flaunting of wealth, position as Emperor and lavish tending to his family and those loyal to him, as well as his swift and aggressive dispatch of opposition reconcile (if at all) with the anti-Royalist [and at times pro-Revolutionary(?)] sentiment he harboured in early life, and to what extent would you say the two styles of rule were similar?

From my perspective the romanticization of Napoleon is ultimately quite similar to that of Alexander the Great. Both were tyrannical rulers who caused the deaths of many innocent people. There are multiple factors that have allowed for their images to present themselves in the positive light there is today. Both created massive amounts of propaganda images that remain in existence today. Both were highly successful military leaders that inspired following generations to emulate them. And most importantly, both have had a long time for nostalgia to rehabilitate their images.

I didn't see this response anywhere here, so I'll add that Napoleon was definitely a brute or at least as much as any other military ruler is. But it's worth noting what he followed. He essentially brought order to France when it was tearing itself apart as well as at war with practically everybody. He was certainly a moderate in the contemporary French political scene even if he was authoritarian.

A good deal of how we see him is related to the fact that most of the rest of Europe was at war with France throughout his rule. Peace rarely lasted and not all of this can be laid at his feet. Almost all of the old monarchies in Europe fought tooth and nail to destroy the remnants of the French Revolution, this was seen as far greater threat to their regimes than Napoleon was.

From where I sit (Toronto, Canada) I wouldn't say that Napoleon is viewed as a positive figure. Good, even great, general yes. But more or less a failure as a leader. His form of government and dynasty didn't really even outlive him. He ended his life as a reviled prisoner and didn't bring resolution to the political or geopolitical issues which characterized his reign. The French Revolution's bloodiest phase was ended, but its effects lingered on arguably until the mid 20th century and his military actions laid the stage for an arch-conservative redrawing of Europe that led ultimately to further conflict. But he did end The Directory and the Revolution and a lot of people were just happy with stability. France was able to pull itself out of the ashes of the Revolution after his departure and rejoin the rest of Europe.

I would say the verdict on Napoleon is mixed unless you're only reading military history.