Liabilities are considered debt if they require interest payments. For example, a loan from a bank would be considered debt since you are required to pay interest on it.
However, accounts payable would not be considered debt since you do not pay interest on it. It’s a net working capital item because it is a non-interest paying liability that is core to operations. Accounts payable represents money owed to suppliers / vendors, and is core to the business since it usually represents purchases of inventory or services directly related to the business’s main products or services. It is typical for suppliers and vendors to allow payment terms of 30-60 days to accommodate their clients.