Zedar82,
Before anything ... welcome to CivFanatics!
Regarding your game;
I agree with some of the comments made here, but respectfully I think that many of the problems are more elemental than which leader might be best suited to your game.
Victory Condition
There is no apparent victory condition in mind. There’s been no war by the looks other than against Barbarians (if even that). While there’s a lot of Wonders built in your empire, there doesn’t seem to be an attempt at leveraging religion for a Cultural win, you’re too small to be confident of a Spaceship victory given the large number of production sites that are usually required, and shooting for a Time victory is hollow at best. If it were me, I’d be looking at a Diplomatic win with some Industrial Age warfare against Russia, England and Rome (taking their cities - adding them you your own empire - increasing your overall population - adding to your vote).
You may hear a lot of players on these boards advise that they don’t have a specific victory target in mind for quite some time in the game, however for a new player I would personally recommend that you begin your game with a specific victory in mind and a fall-back position. I would suggest that you don't want to find yourself halfway through the game without focus.
Settings
I am unsure why you’re playing on Marathon on a Huge map. To me I think you would be well served by playing some games on regulation settings unless you have something in mind that I don’t see. Marathon tends to favour the warmonger approach (units move quicker than the rest of the game), which isn’t what’s happening here in that you're not attacking or mobilising your forces. I suggest that playing more games on standard maps at normal (or if you must; epic) speed will have you playing more games, making more mistakes, learning from those mistakes, having more successes, understanding why you were successful, and retrying with fresh approaches. You may disagree!
Civics
I have to agree with Voice of Unreason – your Civic choices are all over the place. It took me some time when I first got Civ4 to understand the subtleties of each, although in most cases the entry-level Civics are not a good choice. A little more on this later, but there is lots of advice on Civic selection in other threads.
PowerChart
[F9] key and change dropdown from 'Score' to 'Power'.
It is just a gauge, but the PowerChart can give you a pretty good idea where you stand in terms of your military prowess, and if you fall hideously behind the other tribes, you can look like easy pickings, particularly for an aggressive tribe or a spiritual tribe who is of another faith.
Check your standing on the PowerChart from time to time, and adjust your city queues accordingly.
Builds
Many of your current builds are not particularly great. For instance, you are ‘building Research’ in a city that doesn’t have an Observatory. Much of this may have a bit to do with lack of clarity regarding your Victory target and the path to victory.
As before, personally I would say that you have some chance of pulling off a Diplomatic victory by maintaining your excellent relationships with the other tribes on your continent, and look at invading some of the weaker tribes on the other continent. It would seem that the northern ones are in the worst shape, so I would start preparing for an invasion – given your technology path, probably go after Chemistry for Grenadiers, and then Steel for Cannons. You will need lots of units (like 25 Grenadiers and 15 Cannons - possibly more) as well as a large navy to get them there. So – start working on your technology by switching into Representation and Bureaucracy, leverage your widespread Buddhism faith by swapping into a more advanced Religious civic such as Organised Religion or Pacifism while you’re improving your infrastructure and economy. Later on, when you’ve got your desired ‘military technologies’, you might consider Police State, Theocracy and Vassalage to pump out a fast and well-promoted army. In the meantime, you might even send Buddhist Missionaries into Incan cities in order to try and get Huayna Capac to flip to Buddhism, which would strengthen the already good relationship with him.
'No more Mr. Nice Guy!'
You can win by playing passively – indeed I’ve won a few totally conflict-free games, but your chances of winning are almost invariably enhanced by knocking out one or two tribes during the course of the game. It is very difficult to get the critical mass required to win by any victory condition (perhaps other than by Cultural) by not capturing a few neighbouring cities, if not taking out a few neighbouring tribes. Clearly Conquest and Domination will require this of you, but even Spaceship, Diplomatic, and Time victories are very well served by having one of the largest, if not the largest empire.
Civilization IV does not have to be played civilly. I had to train myself not to fear the A.I. tribes, and indeed start giving them quite a bit of grief. It’s important that you don’t become too builder-obsessed and Wonder-obsessed, but instead start pulling together a few big Stacks of Doom and start hitting one of the neighbours around.
In the game you have however, I think that you stand a much better chance of belting around the Confucian tribes on the other continent than backstab your neighbours, but this is because of the position that you’ve now created.
Understand City Specialisation and Food Management
Sisiutil's Strategy Guide for Beginners does a really good job as setting out city specialisation, but has a bag of other invaluable tips.
It’s also important to understand how to count food. Hamburg in your game could be used as an example of too much cottaging and too few farms. There is no benefit in building cottages that can’t be worked because you simply do not have access to the food required to support the citizens to work the cottages. The Biology technology improves your food haul, but the principle's the same - you need to have the food to support the citizen to work the cottage.
Rearranging the current food formation to maximise food;
(Not unhealthy) Citizens require 2

to work a tile, and obviously you can offset food surplus tiles for food deficit ones provided that they balance or else starvation could occur from a net deficit. The city centre gets 2

for free.
There’s a +4

in total, however there are lots of tiles that are ‘food deficit’ tiles that for most of the game can’t be worked without sacrificing another tile. Admittedly, the city will be able to accommodate only two more citizens before hitting unhappiness problems, however these may be addressed with other tactics. If the city is to eventually use all of its tiles it may need to chain irrigate from the river to the south east over the cottages on plains
or look at windmills rather than mines on some of the hills.
City Placement
Your cities are too far apart, and this has almost invited the A.I. to settle around your turf, while you have a load of tiles in your cultural borders that are unworkable because they are outside of any city 'fat-Xs'. On the plus side, rivals' cities such as Zanguldak and Nascu are quite likely to flip to your empire given your reasonable cultural pressure. Perhaps on a huge map you have considered using an alternative strategy such as placing a small number of outer-ring cities with the view to back-filling later, but by the time you have Currency (+1

) and Code of Laws (Courthouses, Caste System) you should be able to expand more freely without sending your economy ‘down the gurgler’.
Frankly, six cities on a huge map in the late Medieval Era is really too small.
Summary
I’ve made a lot of suggestions here, and I hope you find some of them of use. Certainly Sisiutil’s Guide is worth a good read if you have yet to go through it. I would have liked to have played on with your game, but my computer can barely handle huge maps.
Maybe for fun just try to (a.) convert Inca to Buddhism, and (b.) develop massive ‘Stacks of Doom’ (SoDs) of Cannons and Grenadiers with a fleet of Galleons and take out Russia, Rome, and England, and (c.) build the United Nations and go for the Diplomatic win.