I think I've pretty well figured it out. Speaking in terms of the Phanerozoic Era and a bit longer (750 million years or so), our planet is usually more than 7° Celsius warmer than today. The earth has already warmed almost 3° C, half of it before the industrial revolution.
We're still in an ice age now (the ice is just disappearing rapidly). The last ice age ended roughly 280 million years ago (they don't happen often). Humans have speeded up warming dramatically. The oceans are already up 300 feet from their ice age lows. They have 225 more feet to go.
Humans and our evolutionary progenitors have existed only during the ice age of the past 6-8 million years. We can probably extend the current cool period by not putting carbon into the atmosphere (though possibly not indefinitely, and at some point, it may be too late --- possibly now).
Climate is twice as variable when the planet is cooler (as it is now). When the planet is hot, it's basically hot everywhere, and probably too hot for human survival at the equator. The sun is gradually growing warmer. Thus the long-term trend over hundreds of millions of years is almost certainly going to be towards somewhat hotter temperatures.
Modern humans have walked the earth for only 200,000 years, 2/3 of that time only in Africa. It is possible, perhaps probable, that without the recent ice age, we couldn't have come to exist. We were almost extinguished as a species only 70,000 years ago. Could it happen again? We should be alert to the possibility.
Thinking over the next few centuries, I'm pretty sure we'll stop adding carbon to the atmosphere, and we'll probably start removing it. Fossil carbon is limited in supply, and we've already burned most of the easy-to-find fossil carbon. It would be better to use carbon to synthesize organic molecules. To our descendants, burning carbon for fuel will appear incomprehensible. Will the end of carbon burning stop global warming, at least for a while? Not in itself. However, I'm optimistic. I think the current (natural) warming trend can be reversed or slowed, though possibly only temporarily.
It's conceivable, perhaps likely, that humans may eventually learn how to manage global mean temperature for the benefit of biological diversity. The best way to start will be by developing non-carbon forms of energy generation. While solar and wind and other sustainable methods will be helpful, fusion power will eventually transform the power grid.
Though fusion power doesn't generate carbon as a waste product, it releases considerable levels of heat, and thus will still contribute to global warming. It will be better to get started on living without carbon sooner rather than later, but we will eventually need to learn how to manage all forms of human energy generation and to regulate global climate.
If the ice age norm of the past 6 to 8 million years can be sustained, our planet will remain more diverse. It may be that we can achieve this as a long-term climate goal. Much more examination of that question will need to take place than has so far occurred.
A positive and desirable multi-species outcome to the current problem of global warming is possible. We must remember that what we don't know is still markedly greater than what we do know. We have much to learn, and many important decisions to make.
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