It will get a bit tougher later on, but it will still be not too difficult. At least, not compared to the other GBA Fire Emblem games. If you're not paying attention, you could easily find yourself on the receiving end of a fatal blow, so don't get complacent.
"I didn't know there was a point, they're available so i'm using em "
Well, Garcia is one thing, but Seth is the Jeigan for this game... Jeigans are powerful paladins given to you at the beginning of the game for 2 reasons: 1. To trick beginners into using them, wasting a lot of EXP 2. To help out players on beginning hard maps... Which really isn't needed in FE7/FE8... The DS one, for example, is a great example of a FE that requires the use of Jeigan to beat the first few maps. Except that Seth is a Jeigan that can actually get stronger... Ones like the actual Jeigan himself and Marcus are garbage later on... And Garcia is weak, anyways. So you are better off trying to use someone else.
As for if it gets harder later on, yes. And depending on maps, the difficulty can drop low or shoot straight up... It seems you are a beginner? Then this game is perfect. It has the lowest difficulty of the GBA games and a good place to start (then again, FE7 wasn't that hard either, and FE6's main difficult was the sudden reinforcements, which isn't really "difficulty" but just "learn and restart"...). Of course, unlike some people try to say, this doesn't mean it is a bad game. I've enjoyed this game no matter how many times I've played, after all... Still my favorite...
"If you managed to survive the excessive tutorial instructions, you've completed the hardest part of the game."
Hahaha, funny joke. And when it comes to tutorials, FE7's was a bigger pain.
Actually, Seth is not much of a Jeigan. He has decent growths, and therefore will be strong early and decently strong later. Still, I wouldn't have him hog all the Exp, as it'll hamper the progress of your other characters.
Life isn't fair. If it was, we'd all be dead. (Yes, I'm sticking with my old quote)