I saw a skeleton in a mibecraft cave?

Yesterday in minecraft i was mining some iron when i noticed a large cave system ahead of me. I begun lighting torches onwards until suddenly out of the darkness i got hit. I lookwd forward and saw a skeleton emerging from the darkness i quickly ran out of that cave and into the sunlight. Now im afraid to go back in the cave. What shall i do. Should i never go back in the cave? The mob was away in the darkness throwing arrows how can i fight it by the time i reach it it would have killed me with his arrows? Im really scared? Help and do mobs lurk the darkness?

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