Does it need to explain every death though? It's most likely that the people of Spira would had started out as hunter-gatherers much like the people of Earth. As such they should be able to deal with the odd fiend showing up every now and then without too much trouble.

And there doesn't need to be a paradox. The sending was likely created because the amount of people not moving on naturally when they died and becoming fiends was reaching a dangerous level. Quite possibly as a result of the growing population, and in particular the higher population density as large cities were being created.

Zombies are a good comparison here actually. Ya know, they too are dead people coming back to kill the living. With our current world with the billions of people in it, if a zombie outbreak were to happen we'd be pretty screwed. Go back a few thousand years though and I think it would be much more manageable. There would be much less people for it to infect and it would spread much slower. Because of both of those it would be easier to deal with zombies as they turned, rather than letting it get out of control. I imagine the same could be true of fiends in early Spira. It's only as the population became much larger and widespread that they really became a problem. Probably took awhile for people to realise too. Not something you'd think of straight away, but if people noticed the amount of fiends seemed to increase significantly following a large number of deaths, whether those be due to fighting or disease or whatever else, they probably would have worked out that they were directly related pretty quick. That's when they start looking for a solution... and discover the sending rites.

Solid music, graphics, okay battle system.

Shit story, character and weapon design, awful puzzles.

Wish I could see what everyone else sees, especially considering IX exists.  

What everyone else sees is your typical western TV drama plot with stock characters and an OMG TWIST at the end. Which is also why people like meh games like FFVII or horrible games like FFVI.

Gameplay or an interesting world with interesting characters is to no concern to anyone.

To FFX's credit though it does have a notable amount of content and a complex level and battle system. Neither of which are present in FFVII or FFVI for example.

What are your top 3 games of all time? 

You mentioned the food they gathered. I do wonder about that. Did they not eat meat? I mean, like you said there's only really shoopufs and chocobos, and as funny as Kentucky Fried Chocobo sounds.... I'm not really sure people would eat that

Of course there's also the possibility that pyreflies and fiends haven't been around for ever either. I just saw this on the FF wikia too "After Yuna's Calm began, the tradition of performing sendings seems to have ended. Final Fantasy X-2 Ultimania Omega elaborates that pyreflies continued to appear in great numbers as the destruction of Sin had broken the cycle of sending the dead to the Farplane resulting in the sudden increase of fiends, as pyreflies are their lifeforce". If post-Sin Spira doesn't need sendings anymore to prevent fiends occuring, then it's possible pre-Sin Spira was similar.