1. CO2 is currently the highest it has ever been since human civilization has existed (10k years, roughly).
2. CO2 is currently the highest it has ever been since humans have existed (200k years, roughly).
3. CO2 is currently the highest it has ever been since primates have existed (50M years, roughly).
But for the sake of argument let’s say:
4. CO2 may not be the highest it has ever been since mammals have existed (200M years, roughly).
5. CO2 is not the highest it has ever been since multicellular life has existed on land (500M years, roughly).
Fair enough. Maybe 1-3 are less concerning to you than they are to me. When you say "the climate has been warmer in the past and CO2 levels higher" and are referring to a period prior to the existence of primates, it doesn't necessarily make me feel that much better. :) That said I’m nothing close to being expert in this stuff.
It’s interestingly difficult to think about time over so many orders of magnitude.