The obvious response is that Gaza is a very densely populated place, of course there's civilians near any given location, that's not a conspiracy by Hamas. But are there any other talking points I should hit?
(I'm not really a lib in rehab, but this seems like the comm for getting talking points straight)
Ask them to if they also consider this Ukrainian artillery position in a school running track to be a form of human shield use. If not, explain the difference. If so, is Russia justified to level Kiev as Israel has been levelling Gaza?