Well, we had a few things go right in this game:
(1) We had a corner start (should be ~50% on a continents map)
(2) We had a 1-tile choke separating us from the rest of the world. (A Mountain to boot!)
(3) We had three lux within our territory, so we combined with (2) we could expand and grow in peace.
(4) The AI's on our continent seemed to be attacking each other a lot. (That stack of Spanish Knights has been around for about 40 turns, and they still haven't attacked anything.)
And that's it.
Zero resources meant even after our peaceful expansion, we couldn't build a military. The only thing that let us come this far was that our UU didn't require resources.
In addition to lacking fresh water, we also had an awful shape to our portion of the continent. In a normal game one would expect to have 10-12 cities 1st or 2nd ring to the capital. We have enough room to properly build 5. That, combined with the lack of fresh water, meant we were essentially playing a dry, resourceless, 3CC AWE game. Which is kind of ridiculous. If our portion of the continent had more grassland, and room to build 6-8 healthy cities, we might have been able to mount an early MA charge past the choke, and certainly would be able to fend off invasions more easily.
Regardless, I don't see an glaring errors in strategy in this game. We may have been able to go on a Bowman rush earlier, but suffered a Despotism GA. Any cities we captured/founded would be rather corrupt due to the new FP model, and we would have had long supply lines.
About the only thing we could have done differently was have the Spanish start position.

The other two AI on our continent also seem to have lousy shapes to their land.
Oddly, about the only way we could have won this game was to give Nehru another turn at the wheel. Resourceless, bonus-HP knights would have allowed us an offense.
And
Handy, don't worry about the army. Once we didn't have Saltpeter, you didn't have a real choice. An army with a spear on top for defense would be killed by the first Cav it saw. The only useful army would have been a 2-LB, 1 Musket army, which you couldn't build.