That is extremely unlikely. We can measure the spectrum and intensity of incoming solar energy and of outgoing radiation from Earth, and see that we are gaining. We can see that much of that gain is due to incoming energy heating things which re-radiate that energy in infrared which we can see gets trapped by CO2.

We can tell by looking at the isotope distribution of the C in the CO2 where it comes from. CO2 from still living or recently living (say dead for only a few hundred years) has a different isotope distribution than CO2 from long dead or never living sources. This lets us tell that most of the CO2 increase over the last couple hundred years is from burning fossil fuels or an increase in geological processes that release long trapped CO2 such as volcanic activity.

The amount of CO2 in the atmosphere that we can tell from that did not come from living or recently living things matches fairly well with what we know of volcanic activity and how much fossil fuels we burn, giving us enough data to conclude that most of the warming due to CO2 is due to human emitted CO2.

For that to be wrong would require that we have massively overestimated how much fossil fuels we use and massively overlooked a large amount of volcanic activity.