The only basic pieces of information you need to understand climate change are:
1) The greenhouse effect exists. That is, when you have something like glass, it will let energy in in the form of light, but it won't let as much energy escape once it's converted to heat. This concept can be grasped by anyone who has walked into a car that has been parked out in the sun. And by the massive clue in the name, that is the existence of greenhouses.
2) Carbon Dioxide is a greenhouse gas. That is, it acts like glass does in a greenhouse. This is harder to believe from first principles, but it's not that hard to believe. For me the clinching explanation (again, as a kid) was learning Venus was hotter than Mercury. And there is no reason to believe folks are lying about this, and I don't believe anyone is even contesting this.
3) Understanding how fossil fuels came into existence (basically, organic material trapped over centuries in the ground. again, the clue is in the name) and understanding the CO2 lifecycle, and how burning fossil fuels adds material to the CO2 lifecycle that was not there earlier. This isn't something that can be determined easily by a kid from 1st principles, but it's something that no one is really contesting either.
Once you accept these 3 fairly straightforward basic physics phenomena, global warming is inevitable.
The only questions are whether the release of CO2 is significant enough to have an impact, where we have to rely on measurements and scientists. But seeing that there was a fairly standard progression in how deniers would first deny global warming was ever happening, then deny that it was anthropogenic, then claim it wouldnt have as negative an impact, and now claim that well, it's too late...let's look at mitigation; I was able to filter them out when they were at step 1 itself.
Aside: I also want to point out the horrific misunderstanding people have about the terms "global warming" and "climate change" which are fairly self descriptive, but apparently is a nefarious effort to "hide the spike". Global Warming (i.e., more energy in the earth's ecosystem due to the greenhouse effect) leads to Climate Change (that is, changes in our climate behavior).
One is a cause, and the other is the effect. Both are valid and orthogonal concepts, and not some sort of conspiracy.