I'm going to agree with you the standard of carefulness has been at times pretty low. If it moves and looks like it might be Hamas - shoot it. I was also not happy about that incident and others. There were also plenty of friendly fire incidents (where soldiers were killed by other soldiers) and the incident where hostages were killed by other soldiers. The level of "discipline" in the IDF isn't what it used to be and definitely the mood in Israel in the early days of the war was of revenge (though the military is not supposed to be thinking like that).
The other side of this coin is when you fight this kind of fight, in a dense urban environment, where combatants intentionally blend with civilians, and use any imaginable tactic they can to attack you, and put weapon stashes in civilian homes, and tunnel entrances etc. Where the enemy may even want to increase civilian casualties on their side, and when you have infantry and armor fighting day in and day out with no sleep and under constant pressure. You are going to have more of these incidents. There might be some at the margin that are actually war crimes but many are just what happens in this kind of war and in this specific scenario.
I'm not going to judge those people when I'm not in their shoes. Including the people who ordered the strike on that convoy. I am Israeli (who hasn't lived there in a long time, but I served in the distance past in the IDF) and I have spoken to people who have been in Gaza. So I know targeting an international aid group is not who we are. I also know that if it was decided that they were Hamas then they'd get obliterated, so that part is not a surprise.
The other thing I do know for sure, is that Hamas started this war and that Israel can not accept Hamas in Gaza after the war and it can not accept Hamas holding hostages after the war.
I'm not sure I see what Israel can do here in terms of Gazan perception of Israel or why it even matters. Many Gazans hate the Hamas but they have no control.