A generic skeleton wouldn't be very useful, as you need the skeleton to match your images. Creating the bones manually is very easy.
The Photoshop script isn't mainly for creating bones (it can, but you will need to adjust them), instead it's for creating attachments for each of your images.
Note you no longer have to use Photoshop. Spine 4.2 can read a PSD directly, just like the Photoshop script (but with more features and MUCH faster). This means you can use image editing software other than Photoshop, save a PSD, and then give it to Spine. Most image editing software can save a PSD. You can use free software, like Gimp, or paid software, like Affinity Designer.