Very few people supported Trump because they thought he'd be better on Gaza. Some may have chosen to take a gamble on literally anyone because the Dems are so bad on it, but I doubt that represents a major bloc.
On the other hand, I think it does represent a major factor when it comes to the economy. People are dissatisfied with the status quo and Kamala ran on the status quo. Trump was able to present himself as an alternative, and he was the only other choice.
I honestly think she could have not just mobilized more democrats, but also peeled off more republicans by seperaring from Biden's economic policies and presenting a further left alternative. Not everyone who votes republican is ideologically committed.
She did truly so much stuff wrong. The only reason I thought she had any chance at all was because Trump is such a shitty candidate that the bar was very low. She was a bad candidate who never would've won a normal primary, like 2020 showed, and she underperformed downballot candidates all over the place, including Nevada, Arizona, Michigan, and Wisconsin, where democratic senators won or are winning, and which combined make up enough EVs to win (not to mention PA where the senate candidate outperformed Harris but lost by a hair, or NC which elected a democratic governor by a wide margin).
Losing Arab voters was probably enough to cost her the election, but even with them it's doubtful she would've won. There was a 14 point swing among Hispanic voters compared to last election, likely because of the Democrats pivoting right on immigration, and the economy was voters' biggest concern where Harris' messaging was very weak. Fundamentally, this whole strategy that they tried that you apparently like of dismissing everyone's concerns except the moderate republicans who were never going to vote democrat is completely self-defeating.