How do I get away from only playing Mongols?

I always just played Mongols, even as a child. Now that I am playing somewhat seriously, I still only play Mongols. I feel like I just win games because at my shitty level it is very hard to end the game quickly, so I inevitably get to Mangudai+Hussar. It is just such a hard combination for bad players like me to deal with and once I get to imp Mangudai I usually win. I don't think I am learning a lot, though. I literally just try to get to Mangudai, every single game.

When I play another civ, their late game just feels so weak in comparison and as a newer player I have a lot of trouble with ending games early. I completely get bodied against someone with the same elo when I don't pick Mongols.

What other civs have a stellar late game army? What would be a good start to branch away from only playing Mongols?

I have trouble finding information on how to properly end a game early. For example, how exactly does one execute a 1 TC push? How do I translate an early advantage (winning scout war, succesful archer rush, whatever) into actually ending the game instead of just out-ecoing my opponent?

I know these questions are very vague but I think that stems from me not understanding very basic stuff because I could always just lean on my Mangudai.

​

Edit: Elo is in the 1100s, if that makes any difference.