Key thing you want if you want to learn more about photography is the ability to manually control settings, the basic shutter speed and aperture.
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All the fancy features on a $2,000 DSLR camera can be outdone by a $100 camera using manual controls. Creative photography comes from creative control. And all the technology and post processing in the world can't fix a photo that has bad composition.
Most community colleges have intro and advanced photography classes that are open to non students. They're usually pretty inexpensive, and you'll learn the basics of things like composition, exposure, etc.
The only thing I'd say about cameras is that going with a camera that has removable lenses will allow more flexibility through the use of various lenses that you can build an inventory of over time, or as your interest changes in the type of photography get into. I'd start with something like a basic Canon or Nikon camera body, for example. Even look at used ones. What ever lenses you invest in work in will work on newer camera bodies you may upgrade to in the future (do a little homework on compatibility). Canon, in particular, has been maintaining compatibility over many years (from the 80's to the present). Heck, I still use a couple of lenses that were used on my old 35mm film cameras that work just as well on my newest full frame digital SLR's (less a couple of features like stabilization). And I suggest focusing on better lenses than on camera bodies. It's the lenses that can have a bigger impact on image quality. Most of the time, any goofs the camera made (i.e. the
user made with the camera) can be fixed in post processing. But of the image isn't clear through the lens, your options are limited. Having said that, camera body sensor size is a factor to consider as well.
Now... riding trails with a DSLR can be a challenge. It's been one of mine. My daily use DSLR camera is a large full frame sensor Canon body with a batter pack, and a heavy 24-105 lens on it. Way too heavy and big to though in the pack and ride. Not to mention, the thought of crashing with $3k+ of hardware in my pack worries me. I instead switch to my smaller APS-C sensor Canon body, but use the same lens (there's that compatibility advantage). Much lighter and smaller, and fits in my hydration pack's expansion pouch. And instead of a large battery pack, I just take extra batteries if I think I'll need 'em. My point here is more food for thought when considering how you want to invest in photo equipment. Thinking it though up front can save you down the line.
By the way, I focus on DSLR because that's what I invested in years ago, and will continue to build on that. Like
root said, don't get too hung up on SLR. Mirror-less is up and coming, and can be a smaller, lighter alternative for tossing into a pack for riding. But I'd still focus on a mirror-less camera body that supports interchangeable lenses.