What are these Insects?
I'm trying to answer my own question. I did a bit of searching, and I found out that my insect resembles the Mupli beetle the most. From Wikipedia:


  The Mupli beetle, Luprops tristis (ഓട്ടുറുമ in Malayalam), is a plant detritus eating Darkling beetle found in parts of India. The adult beetle is black and around 8 millimeters (0.31 in) long.




I hope someone can verify if my findings are correct or not.