I'd definitely echo the others' sentiments for looking to a decent bike "co-op" where you can pitch in, lend a hand, and learn by doing (while being coached by others who know how to do most fix-it stuff with bikes). It's worth learning how to do chain replacement, shorting the length, tuning the derailleurs, tuning the brakes. Replacement of stuff like the cabling and the headsets, for example, is only a short step beyond those. Yes, some tools are required to do many maintenance items properly, but it's a great skillset to have and helps you learn to know and trust your own bike in a way you'll never get without "knowing" the bike's functions. Basic maintenance know-how can help give you that.

If you have no bike co-op near you, perhaps getting to know several of the nearby (or regional) bike shops and their activities, as many of them will have gatherings of cyclists for weekend rides and the like. You can often pick up a "fix-it buddy" who'd be happy to let you lend a hand during maintenance days. Many (I'd say most) cyclists eventually learn the basics. A small shop might even be willing to let you watch while various basic maintenance jobs are done by them on your bike. (I've got a shop near me that does this, when I've purchased the parts through them and am having them do a parts install I've not yet done myself. They're willing, though some shops likely won't be.)