Not really.You put a lot of thought into this and it is well-written. That doesn't mean we have to agree with this.
If Biden was more popular, she would be running close to him. Harris' limited description of her policies to date sound like Biden 2.0. Why is it unfair they be assessed that way? Harris can always say here's where I would do things differently but we know that won't happen. (Hate Trump or like Trump, the guy puts his own stamp on things.)
The Trudeau/Harper thing isn't comparable. Biden is the current Democrat running the country. The Republican ticket is running against the Democratic ticket.
PS- To hark back to the ad slogan this is not your father's Oldsmobile. If her policies look like and feel like an Oldsmobile, they are her father's Oldsmobile.
Most voters don't vote policies. They vote personality.
KH could repeat Biden's policies and yet attract a completely different type of voter.
Look at Trump. He has effectively no coherent policies, yet manages to attract those voters who love a senile clown who claims immigrants eat dogs.