The only thing he's sitting on the fence on is Brexit. When you'll lose half of your base by backing Remain, lose half your base by backing No Deal and lose half of your base by backing a deal which is neither here nor there, surely you can see why both Labour and Conservatives are split on this? How do you pick a side when millions of people across towns and cities you represent want both to happen? If there was a simple answer to this, both parties would have done it by now. Lib Dems and Brexit had nobody to lose, only votes to gain, so there success can't be compared to performance of the other major parties in my opinion.
In terms of what does he stand for, I thought Corbyn has always been honest and transparent about this, nothing has changed? Increase taxes on the rich instead of austerity measures which hit the poor. He'd like to re-nationalise Energy and Railways who he thinks make too much money or aren't operating effectively/held to account. He wants to protect workers rights so that full/part time, temporary/permanent, everyone is treated the same and to ban zero hour contracts. He wants to remove any element of privatisation within the NHS.
You either predominantly agree with these ideas and you support Labour, or you disagree (which is fine) and your ideals are more closely aligned with the Conservatives.
If at this point you don't understand what Corbyn stands for or why you would vote Labour then you're not in a position to slate him as irrelevant. I'd assume you pick up bits and pieces of information from outlets that would be fundamentally at odds with the above views and so the picture you have of Corbyn is distorted.
Brexit isn't an issue that will take me away from Labour, neither is perceived antisemitism. Both need to be addressed but I don't suddenly believe that because of those two issues, Farage or Boris Johnson will represent me better.