Stalker in the woods

The last time I played Minecraft was a year ago... I decided to play it again.
I started a new world in survival. I spawned in a cave. I saw some lights at the end of the cave. I went after it. I saw a furnace, a crafting table, torches and a chest. Strange, Isn't it? After a while, I saw a tree. I chopped it down and made a small house. I also made a pickaxe, a sword, an axe and more tools. I then went back into the cave to mine some ores. 5 minutes later, when I was finished with mining, I went back to my house. I didn't notice that someone was watching me. So later that day I was exploring the world. I found a dungeon and some loot. I went back to my house.
BOOM!
The house was on fire! I was scared and decided to make another world. I spawned again in the same world and the same cave. Minecraft crashed not long after. I started minecraft again. The menu buttons were different than before. They were red and I saw the background of the nether instead of the overworld. I went back to my world. I saw a guy in front of me.
He said:
HELLO HUMAN.
LEAVE THIS WORLD OR I'M GONNA KILL YOU
PLS LEAVE
PLS LEAVE
PLS LEAVE
PLS LEAVE
Minecraft was crashing.
PLS LEAVE
PLS LEAF
PLS LEA
PLS LEF
PLS STEF
PLS STEF WAKE UP!!
This is part 1 if u want to see more comment down below!