Check out this 2 snipping tool file I made of 2 versions of my CD back cover. The one on the right, it's hard to read the text especially where the black boots and dark areas are. The one on the left, I used opacity on the pic to fade the pic into the background, so the text is more readable.

I wonder how hard it would be to have a combination of the 2. In other words reduced opacity on the left where the text is and full opacity on the right where the picture is and a middle transition blending between the 2?

I thought also it would be nice to move the pic to the right so you see more of the girl and on the left where it's only ocean and land to maybe stretch the pic to make up for the blank space I'd get on the right if I moved the pic over. I used the entire pic to fill this back panel, no cropping.

What you need is a layer mask for the background layer. see https://docs.gimp.org/en/gimp-layer-mask-add.html

Add a white layer mask Layer -> Mask -> Add Layer mask. Anything marked white in the mask is opaque, anything black is transparent, shades of grey various transparency.

The points to note are in the layer dialogue, an active layer has a white border, inactive a black border

see: https://i.imgur.com/DyMjc1C.jpg

Click in the layer mask to make it active.

Draw across the canvas a FG/BG gradient. FG can be a dark grey BG is white.

The shape (linear/circular..),start & end point, offset and direction of the gradient tool all matter and make a difference.

If you do not like the result, fill with white and start again. Because of the transparency, put a white layer underneath.

see: https://i.imgur.com/zOamDfl.jpg

Why use a layer mask? It is non-destructive.

Save your work as a Gimp xcf file, keeps all layers, masks, guides etc. When finished export to your required format, png, jpeg, tiff.

Alternative for your image, change the text colour to white.

Check out this 2 snipping tool file I made of 2 versions of my CD back

I thought also it would be nice to move the pic to the right so you see more of the girl and on the left where it's only ocean and land to maybe stretch the pic to make up for the blank space I'd get on the right if I moved the pic over. I used the entire pic to fill this back panel, no cropping.

A spare half hour so, had to dig up some comparable images.

With the image you are using, a copy paste would work. That left side will take a bit of distortion, although a bit of cloning might eventually be required. Just work on a single image.

Increase the canvas size Image -> Canvas Size. Width only, maybe 300 pix set to all layers.

Make a narrow (say 300 pix) selection on the left side. Copy then paste to get a floating layer.

Resize the floating layer with, dragging to the left. Anchor the floating layer.

Move the whole layer to the right.

Another way, seam carving, uses a Gimp plugin 'liquid rescale' http://liquidrescale.wikidot.com/ Downloads and examples there. The image you are using might prove difficult with this method.

Both these as a demo in a single video https://youtu.be/9TlmZTeECzg duration 6 1/2 mins