I'm not 100% sure on this based on the screenshot, but you can probably easily confirm - is there any other landmass reachable by galleys? If so, then perhaps you could go for GLH and get some cities on another landmass. Other than that, this is a tough start. Get to astro as soon as possible and see if you've got another landmass to settle somewhere, but no doubt, that's much easier said than done.