Who says he is unelectable? A week ago, Brexit was almost unattainable. 15 months ago, a Tory majority was a dream. You cannot call anyone unelectable in the current climate.
There's wacky strangeness due to the vagaries of campaigning - there was a crap Remain campaign this year and an *excellent* Tory campaign (specifically targeting Lib Dems to squeeze via making people scared of the SNP) supported by one of the worst Labour campaigns in recent memory (the Ed stone, the bacon sandwich).
Then there's Corbyn.
We're talking about:
-> A totally split Labour party
-> A voting public that really, really does not like the hard left ("socialists") once you move outside of urban areas (and this trend is more relevant the older the voter)
-> Corbyn's total inability to manage the media (the Vice documentary)
-> The SNP juggernaut blocking any Labour resurgence in Scotland (the only likely SNP casualty in a new GE would be in Edinburgh West)
-> The continual and seemingly accelerating movement of Labour's heartlands towards social conservatism (rise of UKIP) which Corbyn and the wider Labour movement have no strategy for stopping.
Jesus himself would have to go knocking on doors with a red rosette before Labour won a 2016 election - let alone an election headed by Corbyn.
Many who lost hope in Labour got interested again by Corbyn being an actual social-democrat instead of a centrist. My timeline on Facebook is full of Corbyn support.
I know you probably didn't mean it like that, but there's a lot of irony in calling Corbyn a social democrat. The first time Labour went around this rodeo, it was the Gang of Four who took that mantle.
He's not a social democrat - he's a socialist, period. He's also at *least* a sympathiser to the Trotsykites.