Wielding a Sword for Five Hundred Years in the Dungeon, from Monster to Human to the Strongest

I am just a skeleton, and I follow my instinct and attack the humans who visit the copy. One day, I attacked the person who entered the dungeon as usual. Incredibly, I couldn't even touch the corner of that person's clothes. And for some reason, he didn't fight back against me. If he didn't attack me, I would continue to attack him, but the man started teaching me the next way to kill him. Although I don't know the reason, as long as I can defeat this person, I will follow him and continue to learn swordsmanship. The man who lived with me and taught me techniques, without realizing it, I regarded him as my master. Then when Master left this copy, I saw a blow that tore apart time and space. I followed my master and swung the sword to learn that strike. Then I finally completed the blow... And before I knew it, 500 years had passed. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.