Thank you for confirming.
One last effort: try forcing a piece of heavy cardstock paper through the adf (either from the input direction or backwards from below) to dislodge anything else that may be stuck there that you're missing.
If still no change, it would indicate a hardware fault in the auto feed mechanism (bad sensor, bad control board, etc)
These adf components are a "wear item" that fails with age/use. As this is a 2011 model printer, it is well past its 3 year service life, so this type of failure is not surprising to see, and you can expect other components like the printhead to fail soon as well.
While it can be fixed, it is not worthwhile to do so. You would have to, at a minimum, replace the adf assembly, which costs about $150; if the logic board is bad you’re looking at $200-250. For $50-100 you can replace the entire machine with a brand new model, with current technology and a fresh warranty, which makes more sense than buying the new part for an older printer.
Depending how you'd like to proceed, I can advise on finding parts, finding a local repair shop, or recommending replacement options for you. Just let me know.
Best regards, ***** ***** for the news,