Do I attach original W2's to my 2021 NY State Tax Return? (There's already a 'Summary of W2 Statements' section in the printout.)

Yes, you need to include with the mailed NY state tax return for 2021 a copy of all the 2021 W-2's and Form 1099's which show income taxes withheld.

You only mail in the forms ... do not send any worksheets ... those are for your use only.