Statements like “but we already knew” are never helpful. Something like that is really just meant for you to performatively proclaim, “I actually knew this already!”

Plenty of people who aren’t as enlightened as you are just now learning or just coming of age to be politically aware. Maybe they were in one of the various operating religious/political cults in the world today sheltering them from objective reality. Leave some room for them to learn something new and feel ownership in that new awareness.

Just literally zero value in “duh! Tell me something I don’t know!”. If anything, it risks derailing the enthusiasm building in someone who wanted to help who now feels “stupid” and “not in the club” so they get quiet.