Mercari & Poshmark

This year I began selling on Mercari & Poshmark.  Based on my sales report I will be receiving a 1099 from Mercari and may possibly reach enough sales to receive one from Poshmark as well.  All items I have sold have been mostly used items from my personal closet and not sold for profit - like a yard sale or flea market.   Will I be required to file these 1099s and be taxed, since items were sold for under the original purchase prices?