> predictions of climate change have been 100% false

That statement is itself 100% false, so far as I can tell. Here's one example. In 1982, some of Exxon's scientists wrote a memo for their management containing a graph (figure 3, page 7, of http://www.climatefiles.com/exxonmobil/1982-memo-to-exxon-ma...) saying that by 2020 CO2 levels would be in roughly the range 400..430 ppm and global mean temperature would be up by roughly 1..1.3 degrees C compared to 1960. Here we are in 2020 and the figures are about 410ppm and +0.9 degrees C. That matches up pretty well, wouldn't you say?

> For the last 20,2000 years the earth has been warming pretty steadily

What the graph you yourself linked to shows is something very different. There are wild oscillations in the Pleistocene (i.e., before 20k years ago), ending up with temperatures much colder than the present. Then a rapid increase from 20k to 10k years ago. Then near-flat temperatures for the last 10k years. And -- though it's over so short a period that it's hard to see on that graph -- an extremely rapid increase over the last ~50 years.

> All of those have already been disproven as false and not going to happen

How? By whom?

> we are more or less exactly flat

This https://climate.nasa.gov/vital-signs/global-temperature/ is not what I would call "more or less exactly flat".

> look at those spikes ... frequently rapidly spiked up in temperature

You're looking at a portion of the Pleistocene, also known as the last Ice Age. Glaciers came and went, and the Eemian "spike" is one of those periods in which the glaciers melted. So, yes, indeed, temperatures "spiked up" and we had a transition from a large fraction of the earth's land area being covered in ice to hardly any of it being. Are you suggesting that we shouldn't be worried about climate change because the consequences might not be any more severe than those of the melting of an ice sheet covering the whole of Canada?

> it was fantastic for life

Pretty good for life overall, yes, and the climate change we're causing might be too. However, my own interests are parochial enough that I care much more what happens to our species and the others that we've grown to depend on, which is any entirely different question. For instance ...

> The Eocene 50 million years ago was 14 celsius warmer and life thrived

... 50M years ago, sea levels were something like 100m higher than they are now. There's a handy tool at http://www.floodmap.net/ that lets you explore the consequences of a given increase in sea level (though it's a bit glitchy and it looks like maybe it doesn't have data for anything too far from the equator). At 100m, things we would lose include: about half of England and Ireland; all of the Netherlands; half of Belgium; most of western France; all of Senegal, the Gambia, and Guinea-Bissau; huge amounts of the eastern USA including more or less all of Florida, Louisiana, Delaware and Rhode Island.

I'm sure life would thrive. The human race would adapt too, no doubt; we're a very adaptable species. But a whole lot of us would have our homes under water, and large regions of what's now the inhabitable world would become inhospitable to human life. E.g., a temperature rise of 14 degrees C turns San Francisco into Death Valley.