In Greece as I understand it the two organisations doing large-scale "social welfare" work are Syriza and... Golden Dawn.
There are trade unions, women's organisations, leftish civil society organisations, etc in the West Bank. They are rather weaker in Gaza, in part due to Hamas smashing them! There are certainly such organisations in Lebanon.
I'm not arguing that Corbyn should go round making condemnation of Middle Eastern Islamists his main focus. Minimally, I'm arguing that he shouldn't say things that are actively wrong. It is perfectly possible to oppose Israel's wars and the oppression of the Palestinians without doing that. Even if in a given situation you judged it was necessary to speak alongside a Hamas representative of whatever - and I'd be a LOT more sceptical about that than Corbyn seems to be - you wouldn't lavish them with praise.
There was a new contingent of left Labour MPs elected this time, due to the slightly looser party regime under Miliband compared to Blair. Some of them are a bit softer or least more cautious, but I think their election was still important. That in addition to established left MPs, noticeably John McDonnell - who while he doesn't disagree with Corbyn in public in general seems to be more Third Campist. Noticeably on Ukraine, where Corbyn seems to focus solely on the role of NATO while McDonnell has actively supported the Ukraine Solidarity Campaign.
I don't think you want to argue that the small number of left Labour MPs means Corbyn has no option but to big up the likes of Hamas - so can you clarify?