Adobe Shape items are vector files. Essentially the Shape app takes a photo, then uses some combination of the photocopy/threshold/cutout filter from Photoshop and image trace from Illustrator to create a vector shape.
Shape library items are placed as linked images in Photoshop, so they reference the actual library in the "cloud" or the sync'ed library on your system.
You can edit color of the entire shape, or rather apply a color, with any number of methods in Photoshop - Layer Style overlays, clipping layers, etc. This should work well if you just want to change the entire object to a single color or gradient. It's only an issue if you want to create a multi-colored object. Then you need to get into masking and overlays. Since you have the shape, generating well-defined masks shouldn't be too difficult. However, you can not alter the original shape data (color) with Photoshop, The same way you can't alter linked Illustrator documents with just Photoshop.
If you want to edit the vector shapes, you do need Illustrator. In Illustrator the Adobe Shape library items are just standard vector objects and allow any alteration to them. They are placed as live vector objects with no link to the Shape libraries directly.
Note that even with illustrator you can't open placed Shape images from Photoshop. You have to launch AI, and then place the Shape Library item to alter it, then re-save as a new file.
Photoshop is merely not designed to edit vector images directly and Adobe Shape is specifically designed to create vector images.
Possible workaround for not having Illustrator....
The mobile app Adobe Comp will let you place a Library item and alter its color. (Note the mobile app Adobe Illustrator Draw will not work, I tried it.)
- Open a new Comp project
- Place your library item
- Select the item
- Change the color
- Use the send icon.. to
Send to Photoshop CC
This will open the comp image in Photoshop on your desktop. (Assuming the Adobe CC account is the same for the mobile apps and the desktop apps.)
The only issue with this is the Comp project opens on an
artboard in Photoshop, so you will see a white background.
Just drag the layer for the shape outside the
Artboard group in the Layers Panel and you'll have a layer with a changed color, still vector, and a transparent background, all without Illustrator.
It's a few extra steps, and the shape will no longer be linked to your shape library, but it does get around the cost of Illustrator.
For my money, using Comp to alter the color of the shape is much more complicated than simply applying a color overlay Layer Style within Photoshop. But I don't fully understand why you'd need to alter the color of the shape itself in the first place.