I guess that you fail to consider that the "shitload" of CO2 (from all sources, including man-made) account for a tiny fraction of the greenhouse gases in the atmosphere. So if 0.5% constitutes a "shitload", what would you call the other 99.5%?
And since you brought up observations of Mars and Venus, perhaps you can explain how the recent warming trend has also been detected on Mars? That would lead the cause of warming to be something the planets have in common - the Sun. Empirical measurements show solar output higher, so wouldn't you think that the most likely explanation would be the most logical one, rather than simple-minded "explanations" of processes that we don't nearly understand?
First, the Earth's atmosphere consists of about 78% nitrogen, 21% oxygen, 1% argon, and trace other gases (including water of about 0.5% and CO2 of about 0.05%). Nitrogen is not a greenhouse gas, oxygen is not a greenhouse gas, and argon is not a greenhouse gas. Thus, of the 32 K greenhouse effect, CO2 plays a very important role. Water is the dominant greenhouse gas, but it primarily serves to amplify the effect of other greenhouse gases since warmer air can hold more water. Additionally, water isn't as significant as it may appear (having a tenfold higher concentration than CO2) because it will precipitate out at colder elevations. Thus, CO2 and methane are the primary greenhouse gases that are really driving the greenhouse effect (with their effect amplified by the water vapour).
Second, the possible effects of a slight increase in solar intensity have been noted. They are too small to account for the increase in atmospheric temperature if they exist. And even the largest potential effect could only account for about a quarter of the warming that has been observed.