Impossible to answer this one. I mean, how would anyone know how untrustworthy everyone else in history has been?
The question also is based on a "red herring" argument, I think, or maybe I should say a "Straw man" argument. Arguable, Trump is NOT the most untrustworthy human being in history -- but who cares? Why does this matter?
Isn't he untrustworthy ENOUGH? And has he broken enough rules to make him worthy of impeachment? Ditto defeat at the polls by voters in 2020?
Those are relevant questions. But it's useless to debate whether he's the worst liar in history -- above Nero, Stalin, and Louis XI of France (known as the "universal spider" for his deviousness, though he actually was a pretty good king.)
So my answer to you is "probably not, but it doesn't matter." The question is whether he's crooked enough and outrageous enough to impeach.
-- democratic socialist / only the truth is revolutionary