hacker? entity?

Hi. i am reporting a weird expeireince in my world. i was going up to the surface to put stuff in a chest. i saw a white player character for a split second and then dissapeared. when i went down back to my mine ALL my torches were broken and on the ground. i had it so no one could join.

is it a hacker? null? herobrine?? please help i dont want to lose my progress.