Do not stress. Just send copies with OCI.That’s so ridiculously wrong, on the website checklist they are mentioning both originals and copy and originals will be returned in 10-12 days
I know for walk in applications they just see and return originals on the spot but postal ones do require originals atleast in the past when I sent my other2 family members OCI applications I remember I sent originals in postal application.
It’s how things work. On paper and on ground are different. Just finish application with copies and start 2-3 month waiting period.