In hindsight, democrats had a horrible strategy letting Biden run the second time. Harris didn’t have much time to present a good platform that would have been her own - she was already the VP, so she couldn’t go directly against Biden, no one would have bought that.
I think Israel/Palestine gets too much attention. An average voter wanted to hear the candidate say they’ll fix immigration and their personal finances. Harris was not terribly vocal on either (although I believe she would have done just fine on both). What Harris did was mainly obtaining celebrity endorsements, while Trump got headlines with his (arguably crazy) policies that appealed to the simpletons.
Hate and simple answers. Trump will “fix inflation” and “bring jobs back”, what could be better? Don’t ask how or what it will cost.