The ending is the hero leaving the dungeon, it just leaves the question of how they got into it unanswered. The sword was supposed to make you feel safer, it has no practical use, and you don’t even have to pick it up to finish the game. And the second door is not meant to be open, it’s where the old man came from, that’s why if you interact with it, it says you can see footprints coming on the other side.
I hope that answers your questions, and I’m glad you liked the graphics. ✌️