The complexity of Photoshop and Lightroom, and the fact that they are only available as a monthly subscription puts many people off using them. There are alternatives, listed below, which can be bought and owned, though they are not then updated until you upgrade to a newer version.
GIMP is a free, open source photo editor for both Windows and Mac.
Exposure X4 - Used to be called Alien Skin Exposure 4. This is the best Lightroom replacement for organising photos, together with excellent editing using layers in the same way as Photoshop. It also has a wide range of filters to simulate film effects and much more.
Microsoft Photos is included in Windows 10 and does a good basic job of editing.
Apple Photos is included with their devices and is good for basic editing.
Online photo editors such as Flickr and Google Photos are also OK for basic editing.
Dark Table - Free RAW editor for Windows, Mac and Linux. Probably the nearest program to Lightroom, which has even more modules, so you may not need any other editing program with this, though it is not so intuitive and has a steeper learning curve than Lightroom. Good library feature. Ref, Ref.
RawTherapee - Free RAW editor for Windows, Mac and Linux. Steep learning curve but very comprehensive. Good library feature. Ref.
Foxit Photo is similar to Photoshop and can work with JPEG or RAW files.
Adobe DNG Converter is a useful program for converting almost any RAW file into the universal DNG format. This is really useful for converting files which may not be supported in some software, such as that for new cameras.
ON1 - Quick, snappy and professional. Catalogue function is good. Best AI masking of all software. Probably nearest to a Lightroom replacement.
Alien Skin Exposure X4 - Intuitive and professional, however often slows down while rendering. Tethering in real time. Does well with catalogues.
Capture One - Very powerful, professional and snappy. It does everything, however there is a very steep learning curve and the interface is not very user friendly. It is probably better than Lightroom overall but is not for the casual user. Different pricing plans make it economical for Fuji and Sony users but expensive for everyone else.
Luminar 3 - Sluggish, buggy and produces screen artefacts. Lacks refinement, though with many good points.