To open: I am not apologising for what Hamas has done at all. I think their actions are revolting. Whatever your view of the history of the region, the aim to eliminate Israel as a Jewish state is unrealistic, extreme and counterproductive.
Nonetheless, I do find the claim they are using human shields as interesting.
Whatever you think of Hamas' aims and methods (and I strongly disapprove of both), Palestinians engaged in conflict are by necessity fighting a guerrilla war against an occupying power. No, Israel is not in direct control of Gaza -- but it does have the capacity to use overwhelming force against any part of it, so it might as well be for the purposes of fighting a war.
Let's assume we are not pacifists and we think armed struggle is _sometimes_ justified (as do both the US and Israel). From the perspective of someone who viewed the establishment of Israel as illegitimate, and the occupation of Gaza unlawful, and Israel's action in Gaza and the West Bank as immoral, what would be the right course of action here?
From that perspective it might seem reasonable to plan and carry out sabotage against Israeli forces (I know that is not all Hamas have done -- they have also murdered civilians, but this is irrelevant to this argument).
There were many resistance movements in the 20th century that are now approved-of by Israel and allies. Was it illegitimate for French resistance fighters (for example) to plan attacks from civilian villages and hide weapons in farmhouses etc? This accusation of using human shields (which predates the current conflict) sometimes strikes me is part of a process to 'other' the Palestinian cause and render it a priori illegitimate, which does't help anyone.
Edit: I recognise this post could upset some people at the moment. It's really not my intention. It's posed as a genuine question and something for us all to reflect on. I might be wrong/misguided but interested to discuss.