Your point would hold if the national race numbers were permanent. They're not. Kamala has already made gains.
So, will the Senate races and national race fall in line? Probably! But that doesn't mean the Dem senate candidates will collapse. There are clearly enough people willing to vote Democrat in those states, just not for Joe Biden. Well, Joe Biden is gone. That was my point in bringing up the senate polling. There are enough people open to voting Democrat for Kamala to win those states.
It's strange that you can't understand that, but try to waive off senate polling "this early in the cylce." Yes, it's early! That's what I'm telling you. The Democratic candidate just went from an 80 year old white man with extremely visible cognitive decline to a 59 year old black woman. That's a pretty big change. And yet, you're acting like Biden's horrible numbers are set in stone and there's nothing Harris can do to improve them.