I think you are far too negative here.  Leaders won't save us and we shouldn't expect them to. And when was the last time one created a new ideology that was more than a rebranding of old ideas? Frankly in more normal times I'd have little objections to Corbyn's stance. In so many questions the correct answer is "just don't". And the Tories are a ready source for those. Just don't cut social services, privatize the NHS, deliver weapons to Saudi Arabia....
Sure the outreach to economic experts was completely bungled and McDonald's economic statements are worrying conventional very serious person reassurance noises. But then no one close to power anywhere else is offering anything close to a reasonable economic program either. Sanders' program wasn't really either. And just as in the case of Sanders the most important thing here is that he can serve as both a focus point of organization and a showcase that leftists can actually win. Getting either no or slanderous media attention is what every socialist can expect. That's neither here nor there. Of course that leads to a natural tendency to only get news from friendly sources which blinds one to real missteps and irreversible wrong turns.
Which is a good place to place a failure condition. According to the latest I heard on the bureaucratic infighting front team Corbyn now has the majority on the NEC again. If they don't get to revoking the frivolous expulsions within the next few months the party is going nowhere.
And yes I left out Brext. At the moment there really is very little that can be done about it and every position the labour party takes can only hurt their fortunes.