It's just poison. All it does is kill the bacteria. Dead or alive it plugs filters.
Checking/changing the filters is the place to start. Might have to change both if you have primary and secondary. One likely mounted somewhere in the engine space and second one mounted on the engine itself. The early boats weren't all built the same and someone might have changed it so can't really say where to look for them. If you change filters and the engine starts you've pretty well zeroed on on the problem. But it is pretty odd if the engine was running OK, you shut it down, and now it won't start. Typically if filter is plugged it should have shut down or at least slowed the engine down last time it ran.
Can't answer whether you HAVE to bleed the system. It's always a good idea but different engines, filters, etc, are different. On my Cummins/Mercruiser there is a bleed port on top of the engine mounted filter housing and a priming pump. But I'm able to get by without bleeding it as long as I fill the replacement filter with fuel when I install it. The pickup tube being plugged is a thought. There have been reports by some owners that they had trouble with a plastic screen on the pickup getting plugged. If I recall Ranger stopped putting them in but can't recall when. Likely later than 2010. The pickup tube can't be gotten at without cutting an access port in the deck inside the cabin. The pickup is just forward of the cabin door step.