I don't use my Olympus OM1 cameras much nowadays but I do use my Canon EOS50E which is an autofocus camera.
Of course your Canon A1, like my OM1s, is manual-focus only so you don't have a choice of auto or manual focus options but with an auto-focus model you can choose which setting to use, in the same way that you can choose with your A1 whether to use the various auto-exposure options or manual exposure.
Although using auto-anything and everything can make you a bit lazy, there's no doubt that as you get older (and slower!) so do your eyes! Thus auto-focus becomes more and more useful as you get older.
There are many times when I over-ride the auto-focus - macro in particular can be much simpler in manual-focus mode. Just when you're ready to press the shutter a dragonfly, say, may move a fraction of an inch and the auto-focus will suddenly lock on to the background instead of the subject!
Sometimes a low contrast subject will fool the auto-focus which then needs manual over-ride. However, there are times when auto-focus could be a positive boon - setting up a remote control camera at a distance, for instance or birds in flight, when you're concentrating on keeping the subject in the right position in the frame.
Here in the UK, the 'collectability' of some Canon FD lenses has pushed up the price of some second-hand items. I've noticed, for instance, that the old 400mm F4.5 (which is not one of Canon's 'L'-series lenses) is quite high, whilst the 500mmF4.5L, a very high-quality lens can be picked up comparatively cheaply, providing you're not looking for a 'Mint'-condition one.
I believe that Tamron and Cosina still make a few of their lenses in manual-focus versions, though whether anybody keeps them in stock is a different matter.