Progress often happens by virtue of very regular, cyclical movements, and it often happens in fits and starts. Sometimes we lose ground. But as long as a person is living in at least a certain state of health, and as long as a civilization persists in at least a certain state of health, an overall tendency toward learning, maturing, growing, expanding, zesty exploration, does seem to be a general trend, even if it doesn't always happen as fast as we'd like, and as much as we're frustrated by our backsliding. The novelties of the centuries and millennia are conserved, preserved, enriching the present, fertilizing new novelties that will then be conserved into the future. (If there is one! -- None of this should be taken to suggest that this process of civilization can't come to a catastrophic halt or that deep changes aren't called for in order to survive and thrive.)
We mourn the passing of our friends, the disappearance of those lives, with their personalities, relationships, and knowledge. Before we follow them, the adventure of occupying this planet includes taking our intelligence, our awareness, our experience, to ever higher heights, absorbing and assimilating the information and resources coming to us from ourselves, from each other, from our ancestors, and from other sources, transmuting them into groovier, more ethical, more beautiful, more loving patterns.