I also started my wrenching on bikes and mini bikes but never got into the engines. It was more like "I have no idea what that carb does and I better not touch it". Apparently, my Dad used to work on our cars but I more remember him just swearing a bunch and getting super pissed off. Throughout my years as a cyclist, I got to the point where I could disassemble and reassemble a bike completely, do my own repairs and troubleshoot. When I would talk to some people (namely my Dad) about how it really wasn't that complicated it dawned on my that since he held the same opinions towards car, maybe I could tackle car maintenance as well.
After I owned my own car out of college I began browsing a lot on this forum. As issues came up I began tackling them myself - routine and preventative maintenance started falling on my shoulders instead of bringing it to a shop. Oil changes, oil filters, air filters boosted my confidence slightly > spark plugs and wires another boost > brake pads, rotors, throttle body cleaning and MAF I was like I can do this stuff! This spring (with a lot of reading and pondering) I tackled serpentine, water pump, coolant elbows, engine and trans mounts, control arms, all new strut assemblies, and a shift kit / filter and rear calipers. I have to admit I am proud that I have been able to check so many things off my list!
Like others have said start small and build confidence while becoming comfortable around and under you car. I like to go in knowing almost exactly what I'll be doing step by step but other may be different in that regard. I've definitely had some "oh s**t, did I f****d this up?!" moments but patience is key.
Good luck!