I will try to solve your doubt. Gaza is a closed area. You can't just cross freely the frontier unless Israel allows it. Before that, humanitarian organisations are required to inform directly to Israeli army about everything that they want to do, where they want to go, how many, an when. They are clearly identified by a logo at all times. Israel had every single piece of info necessary to avoid bombing aid workers and had it for weeks

Despite that, Israel can't avoid to keep killing this workers; and they were doing the same repeatedly, systematically, for the last six months, in multiple attacks that last tens of minutes (maybe even hours?), while singing "oops!, I did it again".

The theory of the honest mistake is getting really difficult to swallow.