The light that comes from the sun keeps humanity in its current state. Heat doesn't impact that that much. Humanity needs light to go on and if the universe ends, and becomes a cold dark place when eventually even the smallest black holes die out, humanity needs to have gone to another universe if possible or humanity will be wiped out too, assuming humanity will still exist then. No, it doesn't just end with the sun dying. Not even for us.
I was about to say that