Don’t worry, the path you’re taking is perfectly legitimate! you reached one of the endings and are now playing the second half of the game, where it becomes more important to rank well in combat in order to keep your corruption down. If you can make it all the way to the end, the game’s true ending will be available (in the part up the elevator). You can also see the other normal ending if you want still by going up the elevator at the end and doing something different at the triendl end branching point, though I won’t spoil it yet.
If you cannot level up, does it say your level is “MAX”? In that case that’s ok, the game is designed with that in mind. Reverting will become a useful tool for you if you die too many times and your corruption is too high; it will send you back to the start of whichever track/chapter you chose, but it will give you another chance to score better in the fights and keep your corruption lower! It will also let you keep whatever experience, mantras, virtues, etc that you have, so don’t worry about losing those. It’s ok, because learning to get better IS the experience, and you might surprise yourself are how you might do in a track the second time through!
I hope this helps, but if you have any more questions or worries, please feel free to join our discord, link up in the description! We have a very knowledgeable and welcoming community there who can help you through the game, because I know you’ll want to see this through to the end. And like I said in the beginning of the game, I believe in you, and everything will be ok in the end!