Out of curiosity, I downloaded your save and checked it in WorldBuilder.And before people start spamming, "Oh Marathon/Huge is so easy," keep in mind that you started as the Romans with 5 gold. Marathon/Huge multiplies early advantages AND early disadvantages significantly.
On a normal deity huge start, the game would include 10 AI opponents. I noticed in your save you have added 6 more to make a total of 17 opponents. Whenever you crowd the AI, limiting their expansion, you also limit their tech speed, development and ability to produce units.
Depending upon how many cities the AI is limited to makes Deity less daunting for the human player.